diff --git a/airflow/contrib/hooks/azure_container_registry_hook.py b/airflow/contrib/hooks/azure_container_registry_hook.py
index af38c1a94380e..b8604b785005f 100644
--- a/airflow/contrib/hooks/azure_container_registry_hook.py
+++ b/airflow/contrib/hooks/azure_container_registry_hook.py
@@ -16,10 +16,12 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
+"""Hook for Azure Container Registry"""
 
-from airflow.hooks.base_hook import BaseHook
 from azure.mgmt.containerinstance.models import ImageRegistryCredential
 
+from airflow.hooks.base_hook import BaseHook
+
 
 class AzureContainerRegistryHook(BaseHook):
     """
diff --git a/airflow/contrib/hooks/cloudant_hook.py b/airflow/contrib/hooks/cloudant_hook.py
index ac64e8950d99f..a29f71dcb3a81 100644
--- a/airflow/contrib/hooks/cloudant_hook.py
+++ b/airflow/contrib/hooks/cloudant_hook.py
@@ -16,7 +16,7 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-
+"""Hook for Cloudant"""
 from cloudant import cloudant
 
 from airflow.exceptions import AirflowException
diff --git a/airflow/contrib/hooks/databricks_hook.py b/airflow/contrib/hooks/databricks_hook.py
index 077bd9e4c6776..7b8ac5e8b3b98 100644
--- a/airflow/contrib/hooks/databricks_hook.py
+++ b/airflow/contrib/hooks/databricks_hook.py
@@ -16,17 +16,17 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-
+"""Databricks hook."""
 from urllib.parse import urlparse
+from time import sleep
 
 import requests
+from requests import exceptions as requests_exceptions
+from requests.auth import AuthBase
 
 from airflow import __version__
 from airflow.exceptions import AirflowException
 from airflow.hooks.base_hook import BaseHook
-from requests import exceptions as requests_exceptions
-from requests.auth import AuthBase
-from time import sleep
 
 RESTART_CLUSTER_ENDPOINT = ("POST", "api/2.0/clusters/restart")
 START_CLUSTER_ENDPOINT = ("POST", "api/2.0/clusters/start")
@@ -39,29 +39,59 @@
 USER_AGENT_HEADER = {'user-agent': 'airflow-{v}'.format(v=__version__)}
 
 
+class RunState:
+    """
+    Utility class for the run state concept of Databricks runs.
+    """
+    def __init__(self, life_cycle_state, result_state, state_message):
+        self.life_cycle_state = life_cycle_state
+        self.result_state = result_state
+        self.state_message = state_message
+
+    @property
+    def is_terminal(self) -> bool:
+        """True if the current state is a terminal state."""
+        if self.life_cycle_state not in RUN_LIFE_CYCLE_STATES:
+            raise AirflowException(
+                ('Unexpected life cycle state: {}: If the state has '
+                 'been introduced recently, please check the Databricks user '
+                 'guide for troubleshooting information').format(
+                    self.life_cycle_state))
+        return self.life_cycle_state in ('TERMINATED', 'SKIPPED', 'INTERNAL_ERROR')
+
+    @property
+    def is_successful(self) -> bool:
+        """True if the result state is SUCCESS"""
+        return self.result_state == 'SUCCESS'
+
+    def __eq__(self, other):
+        return self.life_cycle_state == other.life_cycle_state and \
+            self.result_state == other.result_state and \
+            self.state_message == other.state_message
+
+    def __repr__(self):
+        return str(self.__dict__)
+
+
+# noinspection PyAbstractClass
 class DatabricksHook(BaseHook):
     """
     Interact with Databricks.
+
+    :param databricks_conn_id: The name of the databricks connection to use.
+    :type databricks_conn_id: str
+    :param timeout_seconds: The amount of time in seconds the requests library
+        will wait before timing-out.
+    :type timeout_seconds: int
+    :param retry_limit: The number of times to retry the connection in case of
+        service outages.
+    :type retry_limit: int
+    :param retry_delay: The number of seconds to wait between retries (it
+        might be a floating point number).
+    :type retry_delay: float
     """
-    def __init__(
-            self,
-            databricks_conn_id='databricks_default',
-            timeout_seconds=180,
-            retry_limit=3,
-            retry_delay=1.0):
-        """
-        :param databricks_conn_id: The name of the databricks connection to use.
-        :type databricks_conn_id: str
-        :param timeout_seconds: The amount of time in seconds the requests library
-            will wait before timing-out.
-        :type timeout_seconds: int
-        :param retry_limit: The number of times to retry the connection in case of
-            service outages.
-        :type retry_limit: int
-        :param retry_delay: The number of seconds to wait between retries (it
-            might be a floating point number).
-        :type retry_delay: float
-        """
+    def __init__(self, databricks_conn_id='databricks_default', timeout_seconds=180, retry_limit=3,
+                 retry_delay=1.0):
         self.databricks_conn_id = databricks_conn_id
         self.databricks_conn = self.get_connection(databricks_conn_id)
         self.timeout_seconds = timeout_seconds
@@ -189,12 +219,24 @@ def submit_run(self, json):
         response = self._do_api_call(SUBMIT_RUN_ENDPOINT, json)
         return response['run_id']
 
-    def get_run_page_url(self, run_id):
+    def get_run_page_url(self, run_id: str) -> str:
+        """
+        Retrieves run_page_url.
+
+        :param run_id: id of the run
+        :return: URL of the run page
+        """
         json = {'run_id': run_id}
         response = self._do_api_call(GET_RUN_ENDPOINT, json)
         return response['run_page_url']
 
-    def get_run_state(self, run_id):
+    def get_run_state(self, run_id: str) -> RunState:
+        """
+        Retrieves run state of the run.
+
+        :param run_id: id of the run
+        :return: state of the run
+        """
         json = {'run_id': run_id}
         response = self._do_api_call(GET_RUN_ENDPOINT, json)
         state = response['state']
@@ -204,23 +246,42 @@ def get_run_state(self, run_id):
         state_message = state['state_message']
         return RunState(life_cycle_state, result_state, state_message)
 
-    def cancel_run(self, run_id):
+    def cancel_run(self, run_id: str) -> None:
+        """
+        Cancels the run.
+
+        :param run_id: id of the run
+        """
         json = {'run_id': run_id}
         self._do_api_call(CANCEL_RUN_ENDPOINT, json)
 
-    def restart_cluster(self, json):
+    def restart_cluster(self, json: dict) -> None:
+        """
+        Restarts the cluster.
+
+        :param json: json dictionary containing cluster specification.
+        """
         self._do_api_call(RESTART_CLUSTER_ENDPOINT, json)
 
-    def start_cluster(self, json):
+    def start_cluster(self, json: dict) -> None:
+        """
+        Starts the cluster.
+
+        :param json: json dictionary containing cluster specification.
+        """
         self._do_api_call(START_CLUSTER_ENDPOINT, json)
 
-    def terminate_cluster(self, json):
+    def terminate_cluster(self, json: dict) -> None:
+        """
+        Terminates the cluster.
+
+        :param json: json dictionary containing cluster specification.
+        """
         self._do_api_call(TERMINATE_CLUSTER_ENDPOINT, json)
 
 
 def _retryable_error(exception):
-    return isinstance(exception, requests_exceptions.ConnectionError) \
-        or isinstance(exception, requests_exceptions.Timeout) \
+    return isinstance(exception, (requests_exceptions.ConnectionError, requests_exceptions.Timeout)) \
         or exception.response is not None and exception.response.status_code >= 500
 
 
@@ -234,38 +295,6 @@ def _retryable_error(exception):
 ]
 
 
-class RunState:
-    """
-    Utility class for the run state concept of Databricks runs.
-    """
-    def __init__(self, life_cycle_state, result_state, state_message):
-        self.life_cycle_state = life_cycle_state
-        self.result_state = result_state
-        self.state_message = state_message
-
-    @property
-    def is_terminal(self):
-        if self.life_cycle_state not in RUN_LIFE_CYCLE_STATES:
-            raise AirflowException(
-                ('Unexpected life cycle state: {}: If the state has '
-                 'been introduced recently, please check the Databricks user '
-                 'guide for troubleshooting information').format(
-                    self.life_cycle_state))
-        return self.life_cycle_state in ('TERMINATED', 'SKIPPED', 'INTERNAL_ERROR')
-
-    @property
-    def is_successful(self):
-        return self.result_state == 'SUCCESS'
-
-    def __eq__(self, other):
-        return self.life_cycle_state == other.life_cycle_state and \
-            self.result_state == other.result_state and \
-            self.state_message == other.state_message
-
-    def __repr__(self):
-        return str(self.__dict__)
-
-
 class _TokenAuth(AuthBase):
     """
     Helper class for requests Auth field. AuthBase requires you to implement the __call__
diff --git a/airflow/contrib/hooks/jira_hook.py b/airflow/contrib/hooks/jira_hook.py
index c8e3add439fda..088e2d2a69dba 100644
--- a/airflow/contrib/hooks/jira_hook.py
+++ b/airflow/contrib/hooks/jira_hook.py
@@ -16,6 +16,7 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
+"""Hook for JIRA"""
 from jira import JIRA
 from jira.exceptions import JIRAError
 
@@ -45,41 +46,41 @@ def get_conn(self):
             get_server_info = True
             validate = True
             extra_options = {}
-            conn = None
+            if not self.jira_conn_id:
+                raise AirflowException('Failed to create jira client. no jira_conn_id provided')
 
-            if self.jira_conn_id is not None:
-                conn = self.get_connection(self.jira_conn_id)
-                if conn.extra is not None:
-                    extra_options = conn.extra_dejson
-                    # only required attributes are taken for now,
-                    # more can be added ex: async, logging, max_retries
+            conn = self.get_connection(self.jira_conn_id)
+            if conn.extra is not None:
+                extra_options = conn.extra_dejson
+                # only required attributes are taken for now,
+                # more can be added ex: async, logging, max_retries
 
-                    # verify
-                    if 'verify' in extra_options \
-                            and extra_options['verify'].lower() == 'false':
-                        extra_options['verify'] = False
+                # verify
+                if 'verify' in extra_options \
+                        and extra_options['verify'].lower() == 'false':
+                    extra_options['verify'] = False
 
-                    # validate
-                    if 'validate' in extra_options \
-                            and extra_options['validate'].lower() == 'false':
-                        validate = False
+                # validate
+                if 'validate' in extra_options \
+                        and extra_options['validate'].lower() == 'false':
+                    validate = False
 
-                    if 'get_server_info' in extra_options \
-                            and extra_options['get_server_info'].lower() == 'false':
-                        get_server_info = False
+                if 'get_server_info' in extra_options \
+                        and extra_options['get_server_info'].lower() == 'false':
+                    get_server_info = False
 
-                try:
-                    self.client = JIRA(conn.host,
-                                       options=extra_options,
-                                       basic_auth=(conn.login, conn.password),
-                                       get_server_info=get_server_info,
-                                       validate=validate,
-                                       proxies=self.proxies)
-                except JIRAError as jira_error:
-                    raise AirflowException('Failed to create jira client, jira error: %s'
-                                           % str(jira_error))
-                except Exception as e:
-                    raise AirflowException('Failed to create jira client, error: %s'
-                                           % str(e))
+            try:
+                self.client = JIRA(conn.host,
+                                   options=extra_options,
+                                   basic_auth=(conn.login, conn.password),
+                                   get_server_info=get_server_info,
+                                   validate=validate,
+                                   proxies=self.proxies)
+            except JIRAError as jira_error:
+                raise AirflowException('Failed to create jira client, jira error: %s'
+                                       % str(jira_error))
+            except Exception as e:
+                raise AirflowException('Failed to create jira client, error: %s'
+                                       % str(e))
 
         return self.client
diff --git a/airflow/contrib/hooks/mongo_hook.py b/airflow/contrib/hooks/mongo_hook.py
index 623d054ca350c..6ab96065d9a08 100644
--- a/airflow/contrib/hooks/mongo_hook.py
+++ b/airflow/contrib/hooks/mongo_hook.py
@@ -16,10 +16,11 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
+"""Hook for Mongo DB"""
 from ssl import CERT_NONE
+from pymongo import MongoClient, ReplaceOne
 
 from airflow.hooks.base_hook import BaseHook
-from pymongo import MongoClient, ReplaceOne
 
 
 class MongoHook(BaseHook):
@@ -83,7 +84,8 @@ def get_conn(self):
 
         return self.client
 
-    def close_conn(self):
+    def close_conn(self) -> None:
+        """Closes connection"""
         client = self.client
         if client is not None:
             client.close()
diff --git a/airflow/contrib/hooks/redis_hook.py b/airflow/contrib/hooks/redis_hook.py
index a63c839e34c85..3ef7e87003cbe 100644
--- a/airflow/contrib/hooks/redis_hook.py
+++ b/airflow/contrib/hooks/redis_hook.py
@@ -24,6 +24,7 @@
 from airflow.hooks.base_hook import BaseHook
 
 
+# noinspection PyAbstractClass
 class RedisHook(BaseHook):
     """
     Wrapper for connection to interact with Redis in-memory data structure store
diff --git a/airflow/contrib/hooks/salesforce_hook.py b/airflow/contrib/hooks/salesforce_hook.py
index 33bfc73b13cf7..ecca48115b590 100644
--- a/airflow/contrib/hooks/salesforce_hook.py
+++ b/airflow/contrib/hooks/salesforce_hook.py
@@ -34,26 +34,24 @@
 
 
 class SalesforceHook(BaseHook):
+    """
+    Create new connection to Salesforce and allows you to pull data out of SFDC and save it to a file.
 
-    def __init__(self, conn_id):
-        """
-        Create new connection to Salesforce and allows you to pull data out of SFDC and save it to a file.
+    You can then use that file with other Airflow operators to move the data into another data source.
 
-        You can then use that file with other Airflow operators to move the data into another data source.
+    :param conn_id: the name of the connection that has the parameters we need to connect to Salesforce.
+        The connection should be type `http` and include a user's security token in the `Extras` field.
+    :type conn_id: str
 
-        :param conn_id: the name of the connection that has the parameters we need to connect to Salesforce.
-            The connection should be type `http` and include a user's security token in the `Extras` field.
-        :type conn_id: str
+    .. note::
+        For the HTTP connection type, you can include a
+        JSON structure in the `Extras` field.
+        We need a user's security token to connect to Salesforce.
+        So we define it in the `Extras` field as `{"security_token":"YOUR_SECURITY_TOKEN"}`
 
-        .. note::
-            For the HTTP connection type, you can include a
-            JSON structure in the `Extras` field.
-            We need a user's security token to connect to Salesforce.
-            So we define it in the `Extras` field as:
-                `{"security_token":"YOUR_SECURITY_TOKEN"}`
+    """
 
-        """
-        super().__init__(conn_id)
+    def __init__(self, conn_id):
         self.conn_id = conn_id
         self.conn = None
 
diff --git a/airflow/contrib/hooks/ssh_hook.py b/airflow/contrib/hooks/ssh_hook.py
index 10085507513d1..b431b9f703928 100755
--- a/airflow/contrib/hooks/ssh_hook.py
+++ b/airflow/contrib/hooks/ssh_hook.py
@@ -16,7 +16,7 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-
+"""Hook for SSH connections."""
 import getpass
 import os
 import warnings
@@ -29,6 +29,7 @@
 from airflow.hooks.base_hook import BaseHook
 
 
+# noinspection PyAbstractClass
 class SSHHook(BaseHook):
     """
     Hook for ssh remote execution using Paramiko.
@@ -238,7 +239,16 @@ def get_tunnel(self, remote_port, remote_host="localhost", local_port=None):
 
         return client
 
-    def create_tunnel(self, local_port, remote_port=None, remote_host="localhost"):
+    def create_tunnel(self, local_port: int, remote_port: int = None, remote_host: str = "localhost") \
+            -> SSHTunnelForwarder:
+        """
+        Creates tunnel for SSH connection [Deprecated].
+
+        :param local_port: local port number
+        :param remote_port: remote port number
+        :param remote_host: remote host
+        :return:
+        """
         warnings.warn('SSHHook.create_tunnel is deprecated, Please'
                       'use get_tunnel() instead. But please note that the'
                       'order of the parameters have changed'
diff --git a/airflow/contrib/hooks/winrm_hook.py b/airflow/contrib/hooks/winrm_hook.py
index 492e375156a11..f81756c6fa816 100644
--- a/airflow/contrib/hooks/winrm_hook.py
+++ b/airflow/contrib/hooks/winrm_hook.py
@@ -17,7 +17,7 @@
 # specific language governing permissions and limitations
 # under the License.
 #
-
+"""Hook for winrm remote execution."""
 import getpass
 
 from winrm.protocol import Protocol
@@ -26,6 +26,8 @@
 from airflow.hooks.base_hook import BaseHook
 
 
+# TODO: Fixme please - I have too complex implementation
+# pylint: disable=too-many-instance-attributes,too-many-arguments,too-many-branches
 class WinRMHook(BaseHook):
     """
     Hook for winrm remote execution using pywinrm.
diff --git a/airflow/hooks/base_hook.py b/airflow/hooks/base_hook.py
index c6b31eb229b84..433a7aec9398f 100644
--- a/airflow/hooks/base_hook.py
+++ b/airflow/hooks/base_hook.py
@@ -16,7 +16,7 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-
+"""Base class for all hooks"""
 import os
 import random
 from typing import Iterable
@@ -62,6 +62,12 @@ def _get_connection_from_env(cls, conn_id):
 
     @classmethod
     def get_connections(cls, conn_id: str) -> Iterable[Connection]:
+        """
+        Get all connections as an iterable.
+
+        :param conn_id connection id
+        :return array of connections
+        """
         conn = cls._get_connection_from_env(conn_id)
         if conn:
             conns = [conn]
@@ -71,6 +77,12 @@ def get_connections(cls, conn_id: str) -> Iterable[Connection]:
 
     @classmethod
     def get_connection(cls, conn_id: str) -> Connection:
+        """
+        Get random connection selected from all connections configured with this connection id.
+
+        :param conn_id connection id
+        :return connection
+        """
         conn = random.choice(list(cls.get_connections(conn_id)))
         if conn.host:
             log = LoggingMixin().log
@@ -79,18 +91,31 @@ def get_connection(cls, conn_id: str) -> Connection:
 
     @classmethod
     def get_hook(cls, conn_id: str) -> "BaseHook":
-        # TODO: set method return type to BaseHook class when on 3.7+. See https://stackoverflow.com/a/33533514/3066428  # noqa: E501
+        """
+        Returns default hook for this connection id.
+        :param conn_id: connection id
+        :return: default hook for this connection
+        """
+        # TODO: set method return type to BaseHook class when on 3.7+.
+        #  See https://stackoverflow.com/a/33533514/3066428
         connection = cls.get_connection(conn_id)
         return connection.get_hook()
 
     def get_conn(self):
+        """Returns connection for the hook."""
         raise NotImplementedError()
 
     def get_records(self, sql):
+        """Returns records for the sql query (for hooks that support SQL)."""
+        # TODO: move it out from the base hook. It belongs to some common SQL hook most likely
         raise NotImplementedError()
 
     def get_pandas_df(self, sql):
+        """Returns pandas dataframe for the sql query (for hooks that support SQL)."""
+        # TODO: move it out from the base hook. It belongs to some common SQL hook most likely
         raise NotImplementedError()
 
     def run(self, sql):
+        """Runs SQL query (for hooks that support SQL)."""
+        # TODO: move it out from the base hook. It belongs to some common SQL hook most likely
         raise NotImplementedError()
diff --git a/airflow/hooks/hdfs_hook.py b/airflow/hooks/hdfs_hook.py
index 31b2f11501a01..8dbd5e7030c3e 100644
--- a/airflow/hooks/hdfs_hook.py
+++ b/airflow/hooks/hdfs_hook.py
@@ -16,21 +16,23 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
+"""Hook for HDFS operations"""
 from airflow import configuration
 from airflow.exceptions import AirflowException
 from airflow.hooks.base_hook import BaseHook
 
 try:
-    from snakebite.client import Client, HAClient, Namenode, AutoConfigClient
+    from snakebite.client import Client, HAClient, Namenode, AutoConfigClient  # pylint: disable=syntax-error
     snakebite_loaded = True
 except ImportError:
     snakebite_loaded = False
 
 
 class HDFSHookException(AirflowException):
-    pass
+    """Exception specific for HDFS"""
 
 
+# noinspection PyAbstractClass
 class HDFSHook(BaseHook):
     """
     Interact with HDFS. This class is a wrapper around the snakebite library.
@@ -87,8 +89,8 @@ def get_conn(self):
                             effective_user=effective_user, use_sasl=use_sasl,
                             hdfs_namenode_principal=hdfs_namenode_principal)
         elif len(connections) > 1:
-            nn = [Namenode(conn.host, conn.port) for conn in connections]
-            client = HAClient(nn, effective_user=effective_user,
+            name_node = [Namenode(conn.host, conn.port) for conn in connections]
+            client = HAClient(name_node, effective_user=effective_user,
                               use_sasl=use_sasl,
                               hdfs_namenode_principal=hdfs_namenode_principal)
         else:
diff --git a/airflow/hooks/slack_hook.py b/airflow/hooks/slack_hook.py
index 953ce319b1eee..bf8cd0fbb198f 100644
--- a/airflow/hooks/slack_hook.py
+++ b/airflow/hooks/slack_hook.py
@@ -16,28 +16,24 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
+"""Hook for Slack"""
 
 from slackclient import SlackClient
 from airflow.hooks.base_hook import BaseHook
 from airflow.exceptions import AirflowException
 
 
+# noinspection PyAbstractClass
 class SlackHook(BaseHook):
     """
-       Interact with Slack, using slackclient library.
-    """
-
-    def __init__(self, token=None, slack_conn_id=None):
-        """
-        Takes both Slack API token directly and connection that has Slack API token.
+    Takes both Slack API token directly and connection that has Slack API token.
 
-        If both supplied, Slack API token will be used.
+    If both supplied, Slack API token will be used.
 
-        :param token: Slack API token
-        :type token: str
-        :param slack_conn_id: connection that has Slack API token in the password field
-        :type slack_conn_id: str
-        """
+    :param token: Slack API token
+    :param slack_conn_id: connection that has Slack API token in the password field
+    """
+    def __init__(self, token: str = None, slack_conn_id: str = None) -> None:
         self.token = self.__get_token(token, slack_conn_id)
 
     def __get_token(self, token, slack_conn_id):
@@ -53,10 +49,16 @@ def __get_token(self, token, slack_conn_id):
             raise AirflowException('Cannot get token: '
                                    'No valid Slack token nor slack_conn_id supplied.')
 
-    def call(self, method, api_params):
-        sc = SlackClient(self.token)
-        rc = sc.api_call(method, **api_params)
+    def call(self, method: str, api_params: dict) -> None:
+        """
+        Calls the clack client.
+
+        :param method: method
+        :param api_params: parameters of the API
+        """
+        slack_client = SlackClient(self.token)
+        return_code = slack_client.api_call(method, **api_params)
 
-        if not rc['ok']:
-            msg = "Slack API call failed ({})".format(rc['error'])
+        if not return_code['ok']:
+            msg = "Slack API call failed ({})".format(return_code['error'])
             raise AirflowException(msg)
diff --git a/airflow/hooks/webhdfs_hook.py b/airflow/hooks/webhdfs_hook.py
index e93877b2ab80c..73314dc14efc9 100644
--- a/airflow/hooks/webhdfs_hook.py
+++ b/airflow/hooks/webhdfs_hook.py
@@ -16,7 +16,7 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-
+"""Hook for Web HDFS"""
 from hdfs import InsecureClient, HdfsError
 
 from airflow import configuration
@@ -27,7 +27,7 @@
 _kerberos_security_mode = configuration.conf.get("core", "security") == "kerberos"
 if _kerberos_security_mode:
     try:
-        from hdfs.ext.kerberos import KerberosClient
+        from hdfs.ext.kerberos import KerberosClient  # pylint: disable=ungrouped-imports
     except ImportError:
         log = LoggingMixin().log
         log.error("Could not load the Kerberos extension for the WebHDFSHook.")
@@ -35,7 +35,7 @@
 
 
 class AirflowWebHDFSHookException(AirflowException):
-    pass
+    """Exception specific for WebHDFS hook"""
 
 
 class WebHDFSHook(BaseHook):
diff --git a/scripts/ci/pylint_todo.txt b/scripts/ci/pylint_todo.txt
index 8a26fca822223..43f0cfe5a845c 100644
--- a/scripts/ci/pylint_todo.txt
+++ b/scripts/ci/pylint_todo.txt
@@ -8,13 +8,11 @@
 ./airflow/contrib/auth/backends/ldap_auth.py
 ./airflow/contrib/auth/backends/password_auth.py
 ./airflow/contrib/hooks/azure_container_instance_hook.py
-./airflow/contrib/hooks/azure_container_registry_hook.py
 ./airflow/contrib/hooks/azure_container_volume_hook.py
 ./airflow/contrib/hooks/azure_cosmos_hook.py
 ./airflow/contrib/hooks/azure_data_lake_hook.py
 ./airflow/contrib/hooks/azure_fileshare_hook.py
 ./airflow/contrib/hooks/cassandra_hook.py
-./airflow/contrib/hooks/cloudant_hook.py
 ./airflow/contrib/hooks/databricks_hook.py
 ./airflow/contrib/hooks/datadog_hook.py
 ./airflow/contrib/hooks/datastore_hook.py
@@ -25,8 +23,6 @@
 ./airflow/contrib/hooks/ftp_hook.py
 ./airflow/contrib/hooks/grpc_hook.py
 ./airflow/contrib/hooks/jenkins_hook.py
-./airflow/contrib/hooks/jira_hook.py
-./airflow/contrib/hooks/mongo_hook.py
 ./airflow/contrib/hooks/openfaas_hook.py
 ./airflow/contrib/hooks/opsgenie_alert_hook.py
 ./airflow/contrib/hooks/pinot_hook.py
@@ -34,7 +30,6 @@
 ./airflow/contrib/hooks/qubole_hook.py
 ./airflow/contrib/hooks/redshift_hook.py
 ./airflow/contrib/hooks/sagemaker_hook.py
-./airflow/contrib/hooks/salesforce_hook.py
 ./airflow/contrib/hooks/segment_hook.py
 ./airflow/contrib/hooks/sftp_hook.py
 ./airflow/contrib/hooks/slack_webhook_hook.py
@@ -44,10 +39,8 @@
 ./airflow/contrib/hooks/spark_sql_hook.py
 ./airflow/contrib/hooks/spark_submit_hook.py
 ./airflow/contrib/hooks/sqoop_hook.py
-./airflow/contrib/hooks/ssh_hook.py
 ./airflow/contrib/hooks/vertica_hook.py
 ./airflow/contrib/hooks/wasb_hook.py
-./airflow/contrib/hooks/winrm_hook.py
 ./airflow/contrib/operators/adls_list_operator.py
 ./airflow/contrib/operators/adls_to_gcs.py
 ./airflow/contrib/operators/awsbatch_operator.py
@@ -155,7 +148,6 @@
 ./airflow/executors/local_executor.py
 ./airflow/executors/sequential_executor.py
 ./airflow/executors/__init__.py
-./airflow/hooks/base_hook.py
 ./airflow/hooks/dbapi_hook.py
 ./airflow/hooks/docker_hook.py
 ./airflow/hooks/druid_hook.py
@@ -170,9 +162,7 @@
 ./airflow/hooks/postgres_hook.py
 ./airflow/hooks/presto_hook.py
 ./airflow/hooks/samba_hook.py
-./airflow/hooks/slack_hook.py
 ./airflow/hooks/sqlite_hook.py
-./airflow/hooks/webhdfs_hook.py
 ./airflow/hooks/zendesk_hook.py
 ./airflow/hooks/__init__.py
 ./airflow/jobs/backfill_job.py
@@ -413,7 +403,6 @@
 ./tests/contrib/hooks/test_spark_sql_hook.py
 ./tests/contrib/hooks/test_spark_submit_hook.py
 ./tests/contrib/hooks/test_sqoop_hook.py
-./tests/contrib/hooks/test_ssh_hook.py
 ./tests/contrib/hooks/test_zendesk_hook.py
 ./tests/contrib/operators/test_aws_sqs_publish_operator.py
 ./tests/contrib/operators/test_azure_container_instances_operator.py
diff --git a/tests/contrib/hooks/test_ssh_hook.py b/tests/contrib/hooks/test_ssh_hook.py
index 15b853a4236b9..2b14bbe1c72cf 100644
--- a/tests/contrib/hooks/test_ssh_hook.py
+++ b/tests/contrib/hooks/test_ssh_hook.py
@@ -18,12 +18,12 @@
 # under the License.
 
 import unittest
+
 from airflow.models import Connection
 from airflow.utils import db
-from tests.compat import mock
-
 from airflow.contrib.hooks.ssh_hook import SSHHook
 
+from tests.compat import mock
 
 HELLO_SERVER_CMD = """
 import socket, sys
@@ -156,11 +156,11 @@ def test_tunnel(self):
         with hook.create_tunnel(2135, 2134):
             server_output = server_handle.stdout.read(5)
             self.assertEqual(server_output, b"ready")
-            s = socket.socket()
-            s.connect(("localhost", 2135))
-            response = s.recv(5)
+            socket = socket.socket()
+            socket.connect(("localhost", 2135))
+            response = socket.recv(5)
             self.assertEqual(response, b"hello")
-            s.close()
+            socket.close()
             server_handle.communicate()
             self.assertEqual(server_handle.returncode, 0)