Helper to add a element to the current section. The Element name
        will be used as an identifier.

def add_element(self, elt):
        """Helper to add a element to the current section. The Element name
        will be used as an identifier."""
        if not isinstance(elt, Element):
            raise TypeError("argument should be a subclass of Element")
        self.elements[elt.get_name()] = elt
        return elt