docs: def last_modified(self):
          """Retrieves the last modified time stamp of the incident/incidents
          from the output response
  
          Returns:
              last_modified(namedtuple): List of named tuples of last modified
              time stamp of the incident/incidents
          """
          resource_list = self.traffic_incident()
          last_modified = namedtuple('last_modified', 'last_modified')
          if len(resource_list) == 1 and resource_list[0] is None:
              return None
          else:
              try:
                  return [last_modified(resource['lastModified'])
                          for resource in resource_list]
              except (KeyError, TypeError):
                  return [last_modified(resource['LastModifiedUTC'])
                          for resource in resource_list]