instance_method/1 declaration:- instance_method +Name/+Arity.
The message Name/Arity is declared to support instance methods in a class. This means that instances of this class, and its descendants, may each define their own methods for this message.
A method defined for this message by the class is considered the default method for the message. An instance that does not define its own method uses the default. Defining a new method overrides this default method; there is no need to explicitly remove it.
An instance method is installed in an instance of the class with the
define_method/3 predicate. An instance method is removed from an
instance of the class, reverting to the default method, with the
undefine_method/3 predicate.
Must occur within the scope of the class definition. Only applies to send messages.
class_method/1, define_method/3, undefine_method/3