source 
   Returns the class which has the method the current class is using. 

tree 
   Returns the inheritance tree of a class. 

sources 
   Returns the sources for a method for a class. Only those parents
   in the tree which define the method are included. 

tree_children 
   All the children who could inherit a method from this class. 
   Four cases and modifiers:
       a. This class is in the tree. 
       b. This class is the first entry in the tree. 
       c. This class is a source of the method and is in the tree. 
       d. This class is the first source of the method and it is in the tree.

subclasses 
   Makes a list of all the subclasses contained within a class. 

source_all 
   Gets all the classes which are a source for a method. 

trees_all 
   Gets all classes that have a method. Gets thier trees or source trees.

function_in_isa
   Detects if a method is inherited or if this class defined the method.
 
method_return_type 
   An internal function just arranging a returned value. 
		   
