docs: def process_base_field(cls, field, key):
          """
          Preprocess field instances.
  
          :param field: Field object
          :param key: Key where field was found
          """
          if not field.name:
              field.name = key
          elif key != field.name:
              if not isinstance(field.alias, list):
                  field.alias = [key]
              else:
                  field.alias.insert(0, key)
              setattr(cls, field.name, field)
  
          cls.prepare_field(field)
  
          if field.alias:
              for alias_name in field.alias:
                  if key is not alias_name:
                      setattr(cls, alias_name, field)