code: def create(cls, name, user=None, network_element=None, domain_name=None,
                 zone=None, executable=None):
          
          ref_list = []
          if user:
              pass
          if network_element:
              ref_list.append(network_element.href)
          if domain_name:
              ref_list.append(domain_name.href)
          if zone:
              ref_list.append(zone.href)
          if executable:
              pass
  
          json = {'name': name,
                  'ref': ref_list}
  
          return ElementCreator(cls, json)
docs: Create a match expression
  
          :param str name: name of match expression
          :param str user: name of user or user group
          :param Element network_element: valid network element type, i.e. host, network, etc
          :param DomainName domain_name: domain name network element
          :param Zone zone: zone to use
          :param str executable: name of executable or group
          :raises ElementNotFound: specified object does not exist
          :return: instance with meta
          :rtype: MatchExpression