      default_error_messages = {
          'invalid': _('Date has wrong format. Use one of these formats instead: {format}.'),
          'datetime': _('Expected a date but got a datetime.'),
      }
      format = api_settings.DATE_FORMAT
      input_formats = api_settings.DATE_INPUT_FORMATS
      datetime_parser = datetime.datetime.strptime
  
      def __init__(self, format=empty, input_formats=None, *args, **kwargs):
          self.format = format if format is not empty else self.format
          self.input_formats = input_formats if input_formats is not None else self.input_formats
 
</s> remove     format = api_settings.TIME_FORMAT
    input_formats = api_settings.TIME_INPUT_FORMATS
 </s> add  </s> remove         self.format = format if format is not empty else self.format
        self.input_formats = input_formats if input_formats is not None else self.input_formats
 </s> add         if format is not empty:
            self.format = format
        if input_formats is not None:
            self.input_formats = input_formats </s> remove         self.format = format if format is not empty else self.format
        self.input_formats = input_formats if input_formats is not None else self.input_formats
 </s> add         if format is not empty:
            self.format = format
        if input_formats is not None:
            self.input_formats = input_formats </s> remove         return value.strftime(self.format)
 </s> add         return value.strftime(output_format) </s> remove         return value.strftime(self.format)
 </s> add         return value.strftime(output_format)
      default_error_messages = {
          'invalid': _('Date has wrong format. Use one of these formats instead: {format}.'),
          'datetime': _('Expected a date but got a datetime.'),
      }


      datetime_parser = datetime.datetime.strptime
  
      def __init__(self, format=empty, input_formats=None, *args, **kwargs):
          self.format = format if format is not empty else self.format
          self.input_formats = input_formats if input_formats is not None else self.input_formats
keep keep keep keep replace replace keep keep keep keep keep
 Access settings lazily, not at module import 
rest_framework/fields.py