Parse the aggregate from the provided parent XML element.

def parse_from_parent(
            self,
            parent,  # type: ET.Element
            state  # type: _ProcessorState
    ):
        # type: (...) -> Any
        """Parse the aggregate from the provided parent XML element."""
        parsed_dict = self._dictionary.parse_from_parent(parent, state)
        return self._converter.from_dict(parsed_dict)