feat: Add useful info when using on terminal

Instead of getting info about memory position, now we receive info that
helps us navigate the nginx conf structure on some cases. For example:
Before: <nginx.Key object at 0x7fe420e7c2b0>
After: <nginx.Key object (log_format)>

nginx.py

@@ -252,6 +252,9 @@ def __init__(self, comment, inline=False):
         self.comment = comment
         self.inline = inline
 
+    def __repr__(self):
+        return "<nginx.Comment object ({0})>".format(self.comment)
+
     @property
     def as_list(self):
         """Return comment as nested list of strings."""
@@ -299,6 +302,9 @@ def __init__(self, value, *args):
         super(Location, self).__init__(value, *args)
         self.name = 'location'
 
+    def __repr__(self):
+        return "<nginx.Location object ({0})>".format(self.value)
+
 
 class Events(Container):
     """Container for Event-based options."""
@@ -344,6 +350,9 @@ def __init__(self, value, *args):
         super(Upstream, self).__init__(value, *args)
         self.name = 'upstream'
 
+    def __repr__(self):
+        return "<nginx.Upstream object ({0})>".format(self.value)
+
 
 class Geo(Container):
     """
@@ -366,6 +375,9 @@ def __init__(self, value, *args):
         super(Map, self).__init__(value, *args)
         self.name = 'map'
 
+    def __repr__(self):
+        return "<nginx.Map object ({0})>".format(self.value)
+
 
 class Stream(Container):
     """Container for stream sections in the main NGINX conf file."""
@@ -388,6 +400,9 @@ def __init__(self, name, value):
         self.name = name
         self.value = value
 
+    def __repr__(self):
+        return "<nginx.Key object ({0})>".format(self.name)
+
     @property
     def as_list(self):
         """Return key as nested list of strings."""

tests.py

@@ -39,6 +39,11 @@
 {
     server unix:/tmp/php-fcgi.socket;
 }
+map $request_body $tmp_body
+{
+    "" "-";
+    default $request_body;
+}
 server
 {
 listen 80;  # This comment should be present;
@@ -354,6 +359,25 @@ def test_server_without_last_linebreak(self):
         self.assertTrue(nginx.loads(TESTBLOCK_CASE_13) is not None)
         self.assertTrue(nginx.loads(TESTBLOCK_CASE_14) is not None)
 
+    def test_useful_info_on_terminal(self):
+        data = nginx.loads(TESTBLOCK_CASE_2)
+
+        upstream = data.children[0]
+        self.assertEqual(str(upstream), '<nginx.Upstream object (php)>')
+
+        key = upstream.children[0]
+        self.assertEqual(str(key), '<nginx.Key object (server)>')
+
+        nginx_map = data.children[1]
+        self.assertEqual(str(nginx_map), '<nginx.Map object ($request_body $tmp_body)>')
+
+        server = data.children[2]
+        comment = server.children[1]
+        self.assertEqual(str(comment), '<nginx.Comment object (This comment should be present;)>')
+
+        location = server.children[-1]
+        self.assertEqual(str(location), '<nginx.Location object (/)>')
+
 
 if __name__ == '__main__':
     unittest.main()