Add Python scripts.

.gitignore

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+.idea
+.pytest_cache
+venv
+**/*.pyc
+env
+__pycache__
+.vscode

README.md

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+# Playground and Cheatsheet for Learning Python
+
+> This is a collection of Python scripts that are split by [topics](#table-of-contents) and contain 
+code examples with explanations, different use cases and links to further readings.
+
+It is a **playground** because you may change or add the code to see how it works 
+and [test it out](#testing-the-code) using assertions. It also allows you 
+to [lint the code](#linting-the-code) you've wrote and check if it fits to Python code style guide.
+Altogether it might make your learning process to be more interactive and it might help you to keep 
+code quality pretty high from very beginning.
+
+It is a **cheatsheet** because you may get back to these code examples once you want to recap the 
+syntax of [standard Python statements and constructions](#table-of-contents). Also because the 
+code is full of assertions you'll be able to see expected functions/statements output right away
+without launching them.
+
+## How to Use This Repository
+
+Each Python script in this repository has the following structure:
+
+```python
+"""Lists  <--- Name of the topic here
+
+# @see: https://www.learnpython.org/en/Lists  <-- Link to further readings goes here
+
+Here might go more detailed explanation of the current topic (i.e. general info about Lists).
+"""
+
+
+def test_list_type():
+    """Explanation of sub-topic goes here.
+    
+    Each file contains test functions that illustrate sub-topics (i.e. lists type, lists methods).
+    """
+
+    # Here is an example of how to build a list.  <-- Comments here explain the action
+    squares = [1, 4, 9, 16, 25]
+
+    # Lists can be indexed and sliced. 
+    # Indexing returns the item.
+    assert squares[0] == 1  # <-- Assertions here illustrate the result.
+    # Slicing returns a new list.
+    assert squares[-3:] == [9, 16, 25]  # <-- Assertions here illustrate the result.
+```
+
+So normally you might want to do the following:
+
+- [Find the topic](#table-of-contents) you're want to learn or recap.
+- Read comments and/or documentation that is linked in each script's docstring (as in example above). 
+- Look at code examples and assertions to see usage examples and expected output.
+- Change code or add new assertions to see how things work.
+- [Run tests](#testing-the-code) and [lint the code](#linting-the-code) to see if it work and is 
+written correctly.
+
+## Table of Contents
+
+1. **Getting Started**
+    - [What is Python](src/getting_started/what_is_python.md)
+    - [Python Syntax](src/getting_started/python_syntax.md)
+    - [Variables](src/getting_started/test_variables.py)
+2. **Operators**
+    - [Arithmetic Operators](src/operators/test_arithmetic.py) (`+`, `-`, `*`, `/`, `//`, `%`, `**`)
+    - [Bitwise Operators](src/operators/test_bitwise.py) (`&`, `|`, `^`, `>>`, `<<`, `~`)
+    - [Assignment Operators](src/operators/test_assigment.py) (`=`, `+=`, `-=`, `/=`, `//=` etc.)
+    - [Comparison Operator](src/operators/test_comparison.py) (`==`, `!=`, `>`, `<`, `>=`, `<=`)
+    - [Logical Operators](src/operators/test_logical.py) (`and`, `or`, `not`)
+    - [Identity Operators](src/operators/test_identity.py) (`is`, `is not`)
+    - [Membership Operators](src/operators/test_membership.py) (`in`, `not in`)
+3. **Data Types**
+    - [Numbers](src/data_types/test_numbers.py) (including booleans)
+    - [Strings](src/data_types/test_strings.py) and their methods
+    - [Lists](src/data_types/test_lists.py) and their methods (including list comprehensions)
+    - [Tuples](src/data_types/test_tuples.py)
+    - [Sets](src/data_types/test_sets.py) and their methods
+    - [Dictionaries](src/data_types/test_dictionaries.py)
+    - [Type Casting](src/data_types/test_type_casting.py)
+4. **Control Flow**
+    - [The `if` statement](src/control_flow/test_if.py)
+    - [The `for` statement](src/control_flow/test_for.py) (and `range()` function)
+    - [The `while` statement](src/control_flow/test_while.py)
+    - [The `try` statements](src/control_flow/test_try.py)
+    - [The `break` statement](src/control_flow/test_break.py)
+    - [The `continue` statement](src/control_flow/test_break.py)
+5. **Functions**
+    - [Function Definition](src/functions/test_function_definition.py) (`def` and `return` statements)
+    - [Default Argument Values](src/functions/test_function_default_arguments.py)
+    - [Keyword Arguments](src/functions/test_function_keyword_arguments.py)
+    - [Arbitrary Argument Lists](src/functions/test_function_arbitrary_arguments.py)
+    - [Unpacking Argument Lists](src/functions/test_function_unpacking_arguments.py) (`*` and `**` statements)
+    - [Lambda Expressions](src/functions/test_lambda_expressions.py) (`lambda` statement)
+    - [Documentation Strings](src/functions/test_function_documentation_string.py)
+    - [Function Annotations](src/functions/test_function_annotations.py)
+6. **Classes**
+    - [Class Definition](src/classes/test_class_definition.py) (`class` statement)
+    - [Class Objects](src/classes/test_class_objects.py)
+    - [Instance Objects](src/classes/test_instance_objects.py)
+    - [Method Objects](src/classes/test_method_objects.py)
+    - [Class and Instance Variables](src/classes/test_class_and_instance_variables.py)
+    - [Inheritance](src/classes/test_inheritance.py)
+    - [Multiple Inheritance](src/classes/test_multiple_inheritance.py)
+7. **Modules**
+    - [Modules](src/modules/test_modules.py) (`import` statement)
+    - [Packages](src/modules/test_packages.py)
+8. **Errors and Exceptions**
+    - [Handling Exceptions](src/exceptions/test_handle_exceptions.py) (`try` statement)
+    - [Raising Exceptions](src/exceptions/test_raise_exceptions.py) (`raise` statement) 
+9. **Files**
+    - [Reading and Writing](src/files/test_file_reading.py) (`with` statement)
+    - [Methods of File Objects](src/files/test_file_methdos.py)
+10. **Additions**
+    - [The `pass` statement](src/additions/test_pass.py)
+    - [Generators](src/additions/test_generators.py) (`yield` statement)
+11. **Brief Tour of the Standard Libraries**
+    - [Serialization](src/standard_libraries/test_json.py) (`json` library)
+    - [File Wildcards](src/standard_libraries/test_glob.py) (`glob` library)
+    - [String Pattern Matching](src/standard_libraries/test_re.py) (`re` library)
+    - [Mathematics](src/standard_libraries/test_math.py) (`math`, `random`, `statistics` libraries)
+    - [Dates and Times](src/standard_libraries/test_datetime.py) (`datetime` library)
+    - [Data Compression](src/standard_libraries/test_zlib.py) (`zlib` library)
+
+## Prerequisites
+
+**Installing Python**
+
+Make sure that you have [Python3 installed](https://realpython.com/installing-python/) on your machine.
+
+You might want to use [venv](https://docs.python.org/3/library/venv.html) standard Python library
+to create virtual environments and have Python, pip and all dependent packages to be installed and 
+served from the local project directory to avoid messing with system wide packages and their 
+versions.
+
+Depending on your installation you might have access to Python3 interpreter either by
+running `python` or `python3`. The same goes for pip package manager - it may be accessible either
+by running `pip` or `pip3`.
+
+You may check your Python version by running:
+
+```bash
+python --version
+```
+
+Note that in this repository whenever you see `python` it will be assumed that it is Python **3**.
+
+**Installing dependencies**
+
+Install all dependencies that are required for the project by running:
+
+```bash
+pip install -r requirements.txt
+```
+
+## Testing the Code
+
+Tests are made using [pytest](https://docs.pytest.org/en/latest/) framework.
+
+You may add new tests for yourself by adding files and functions with `test_` prefix
+(i.e. `test_topic.py` with `def test_sub_topic()` function inside).
+
+To run all the tests please execute the following command from the project root folder:
+
+```bash
+pytest
+```
+
+To run specific tests please execute:
+
+```bash
+pytest ./path/to/the/test_file.py
+```
+
+## Linting the Code
+
+Linting is done using [pylint](http://pylint.pycqa.org/) library.
+
+To check if the code is written with respect
+to [PEP 8](https://www.python.org/dev/peps/pep-0008/) style guide please run:
+
+```bash
+pylint ./src/
+```
+
+In case if linter will detect error (i.e. `missing-docstring`) you may want to read more about 
+specific error by running:
+
+```bash
+pylint --help-msg=missing-docstring
+```