fails:Object#is_a? returns true if given class is the object's class
fails:Object#is_a? returns true if given class is an ancestor of the object's class
fails:Object#is_a? returns false if the given class is not object's class nor an ancestor
fails:Object#is_a? returns true if given a Module that is included in object's class
fails:Object#is_a? returns true if given a Module that is included one of object's ancestors only
fails:Object#is_a? returns true if given a Module that object has been extended with
fails:Object#is_a? returns false if given a Module not included in object's class nor ancestors
fails:Object#is_a? raises a TypeError if given an object that is not a Class nor a Module
