@staticmethod
def _update_status(old_status, new_status):
    """
        Set status messages.
        :param old_status: original status
        :param new_status: changed status
        :return: status dictionary
        """
    old_status['catalogs']['valid'] += new_status['catalogs']['valid']
    old_status['catalogs']['invalid'] += new_status['catalogs']['invalid']
    old_status['collections']['valid'] += new_status['collections']['valid']
    old_status['collections']['invalid'] += new_status['collections']['invalid'
        ]
    old_status['items']['valid'] += new_status['items']['valid']
    old_status['items']['invalid'] += new_status['items']['invalid']
    old_status['unknown'] += new_status['unknown']
    return old_status
