@staticmethod<EOL><INDENT>def metadata_updated_on(item):<DEDENT>
ts = str_to_datetime(item['<STR_LIT>'])<EOL>return ts.timestamp()<EOL>
Extracts the update time from a RSS item.

        The timestamp is extracted from 'published' field.
        This date is a datetime string that needs to be converted to
        a UNIX timestamp float value.

        :param item: item generated by the backend

        :returns: a UNIX timestamp