def only_extras(self):
known = [key for key in self._dict.keys() if key in self.c_param]<EOL>if not known:<EOL><INDENT>return True<EOL><DEDENT>else:<EOL><INDENT>return False<EOL><DEDENT>
Return True if this instance only has key,value pairs for keys
that are not defined in c_params.

:return: True/False