code: def is_opus_maximum(self):
          
          opmax = self._get_opus_maximum()
          types = self.ecrm_P2_has_type
  
          if opmax in types:
              return True
          else:
              if len(self.author.get_works()) == 1:
                  return True
              else:
                  return False
docs: Check whether the work is the author's opus maximum.
  
          Two cases:
          1. the work is flagged as opus max
          2. there is only one work by this author
  
          :return: boolean