@staticmethod
def metadata_updated_on(item):
    """Extracts and coverts the update time from a Phabricator item.

        The timestamp is extracted from 'dateModified' field. This date is
        in UNIX timestamp format but needs to be converted to a float
        number.

        :param item: item generated by the backend

        :returns: a UNIX timestamp
        """
    return float(item['fields']['dateModified'])
