This method clones AttributeMap object.

        Returns AttributeMap object that has the same values with the
        original one.

def clone(self):
        """ This method clones AttributeMap object.

        Returns AttributeMap object that has the same values with the
        original one.
        """

        cloned_filters = [f.clone() for f in self.filters]
        return self.__class__(cloned_filters, self.attr_type, self.attr_value)