added usage documentation links to docstrings.

pypat/behavioral/chain.py

@@ -5,7 +5,8 @@ class ChainLink(object, metaclass=ABCMeta):
     """
     Abstract ChainLink object as part of the Chain of Responsibility pattern.
 
-    External Chain of Responsibility Pattern documentation: U{https://en.wikipedia.org/wiki/Chain-of-responsibility_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Chain of Responsibility Pattern documentation: U{https://en.wikipedia.org/wiki/Chain-of-responsibility_pattern}
     """
     def __init__(self):
         """
@@ -44,7 +45,8 @@ class Chain(object, metaclass=ABCMeta):
     """
     Abstract Chain class as part of the Chain of Responsibility pattern.
 
-    External Chain of Responsibility Pattern documentation: U{https://en.wikipedia.org/wiki/Chain-of-responsibility_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Chain of Responsibility Pattern documentation: U{https://en.wikipedia.org/wiki/Chain-of-responsibility_pattern}
     """
     def __init__(self, chainlink):
         """

pypat/behavioral/command.py

@@ -5,7 +5,8 @@ class Receiver(object, metaclass=ABCMeta):
     """
     Abstract receiver class as part of the Command pattern.
 
-    External Command Pattern documentation: U{https://en.wikipedia.org/wiki/Command_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Command Pattern documentation: U{https://en.wikipedia.org/wiki/Command_pattern}
     """
     def action(self, name, *args, **kwargs):
         """
@@ -26,7 +27,8 @@ class Command(object, metaclass=ABCMeta):
     """
     Abstract Command class as part of the Command pattern.
 
-    External Command Pattern documentation: U{https://en.wikipedia.org/wiki/Command_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Command Pattern documentation: U{https://en.wikipedia.org/wiki/Command_pattern}
     """
     def __init__(self, receiver):
         """
@@ -56,7 +58,8 @@ class Invoker(object, metaclass=ABCMeta):
     """
     Abstract Invoker class as part of the Command pattern.
 
-    External Command Pattern documentation: U{https://en.wikipedia.org/wiki/Command_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Command Pattern documentation: U{https://en.wikipedia.org/wiki/Command_pattern}
     """
     def __init__(self, valid_commands):
         """

pypat/behavioral/iterator.py

@@ -5,7 +5,8 @@ class Iterator(object):
     """
     An Iterator class for the Iterator design pattern.
 
-    External Iterator Pattern documentation: U{https://en.wikipedia.org/wiki/Iterator_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Iterator Pattern documentation: U{https://en.wikipedia.org/wiki/Iterator_pattern}
     """
     def __init__(self, iterable):
         """
@@ -27,7 +28,8 @@ class Iterable(object, metaclass=ABCMeta):
     """
     An abstract class representing an Iterable object as part of the Iterator design pattern.
 
-    External Iterator Pattern documentation: U{https://en.wikipedia.org/wiki/Iterator_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Iterator Pattern documentation: U{https://en.wikipedia.org/wiki/Iterator_pattern}
     """
     @abstractmethod
     def __next__(self):

pypat/behavioral/mediator.py

@@ -5,7 +5,8 @@ class Mediator(object):
     """
     Mediator class as part of the Mediator design pattern.
 
-    External Mediator Pattern documentation: U{https://en.wikipedia.org/wiki/Mediator_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Mediator Pattern documentation: U{https://en.wikipedia.org/wiki/Mediator_pattern}
     """
     def __init__(self):
         """

pypat/behavioral/memento.py

@@ -5,7 +5,8 @@ class Memento(object):
     """
     Memento class as part of the Memento design pattern.
 
-    External Memento Pattern documentation: U{https://en.wikipedia.org/wiki/Memento_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Memento Pattern documentation: U{https://en.wikipedia.org/wiki/Memento_pattern}
     """
     def __init__(self, state):
         """
@@ -25,7 +26,8 @@ class Originator(object):
     """
     Originator base class as part of the Memento design pattern.
 
-    External Mediator Pattern documentation: U{https://en.wikipedia.org/wiki/Memento_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Mediator Pattern documentation: U{https://en.wikipedia.org/wiki/Memento_pattern}
     """
     def commit(self):
         """

pypat/behavioral/null.py

@@ -2,7 +2,8 @@ class Null(object):
     """
     A Null object class as part of the Null object design pattern.
 
-    External Null Object Pattern documentation: U{https://en.wikipedia.org/wiki/Null_Object_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Null Object Pattern documentation: U{https://en.wikipedia.org/wiki/Null_Object_pattern}
     """
     def __init__(self, *args, **kwargs):
         """

pypat/behavioral/observer.py

@@ -5,7 +5,8 @@ class Observer(object, metaclass=ABCMeta):
     """
     Abstract Observer class as part of the Observer design pattern.
 
-    External Observer Pattern documentation: U{https://en.wikipedia.org/wiki/Observer_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Observer Pattern documentation: U{https://en.wikipedia.org/wiki/Observer_pattern}
     """
     @abstractmethod
     def update(self, **state):
@@ -19,7 +20,8 @@ class Observable(object):
     """
     Base Observable class as part of the Observer design pattern.
 
-    External Observer Pattern documentation: U{https://en.wikipedia.org/wiki/Observer_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Observer Pattern documentation: U{https://en.wikipedia.org/wiki/Observer_pattern}
     """
     def __init__(self):
         """

pypat/behavioral/visitor.py

@@ -5,7 +5,8 @@ class Visitor(metaclass=ABCMeta):
     """
     Abstract Visitor class as part of the Visitor Design Pattern.
 
-    External Visitor Design Pattern documentation: U{https://en.wikipedia.org/wiki/Visitor_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Visitor Design Pattern documentation: U{https://en.wikipedia.org/wiki/Visitor_pattern}
     """
     def visit(self, node, *args, **kwargs):
         """
@@ -42,7 +43,8 @@ class Visitee(object):
     """
     A base class for objects that wish to be able to be visited by a Visitor class.
 
-    External Visitor Design Pattern documentation: U{https://en.wikipedia.org/wiki/Visitor_pattern}
+    - External Usage documentation: U{https://github.com/tylerlaberge/PyPatterns/wiki/Behavioral-Pattern-Usage}
+    - External Visitor Design Pattern documentation: U{https://en.wikipedia.org/wiki/Visitor_pattern}
     """
     def accept(self, visitor, *args, **kwargs):
         """