Return if a method exists for the current instance.

        # Arguments
            key: The method name.

        # Returns:
            bool:
                * True if the current instance has the provided method.
                * False else.

def has_method(self, key: str) -> bool:
        """ Return if a method exists for the current instance.

        # Arguments
            key: The method name.

        # Returns:
            bool:
                * True if the current instance has the provided method.
                * False else.

        """
        return hasattr(self.__class__, key) and callable(getattr(self.__class__, key))