ENH: Added documentation for role.py

ml/role.py

-from ml.identifier import ID
-from abc import ABC
+"""This module implements the role class."""
+
 import sys
+from abc import ABC
+from ml.identifier import ID
+
 
 class Role(ABC):
+    """Each Role class manages a role which can be assigned to things."""
     def __init__(self, name="", identifier=""):
+        """Constructs a new Role class object with the given name and
+        identifier.
+
+        :param name: Name of the feature
+        :param identifier: Identifier of the feature
+        """
+
         self.__identifier = ID(identifier).identifier
         self.__name = name
+
+        # TODO: Remove code duplication (feature.py).
         if 'ml\\fml40' in sys.modules[self.__class__.__module__].__file__:
             self.__class_name = "fml40::{}".format(self.__class__.__name__)
         else:
@@ -14,22 +27,53 @@ def __init__(self, name="", identifier=""):
 
     @property
     def class_name(self):
+        """Sets __class_name to value.
+
+        :param value: New class name
+
+        """
         return self.__class_name
 
     @property
     def name(self):
+        """Returns the object's name.
+
+        :returns: Name of the object
+        :rtype: str
+
+        """
+
         return self.__name
 
     @name.setter
     def name(self, value):
+        """Sets __name to value.
+
+        :param value: New name
+
+        """
+
         self.__name = value
 
     @property
     def identifier(self):
+        """Returns the object's indentifier.
+
+        :returns: Identifier
+        :rtype: str
+
+        """
+
         return self.__identifier
 
     @identifier.setter
     def identifier(self, value):
+        """Builds an ID object from value and assigns the resulting identifier
+        to __identifier.
+
+        :param value: Proposal of the identifier
+        """
+
         self.__identifier = ID(value).identifier
 
     def to_json(self):