      """
  
      default_error_messages = {
          'does_not_exist': _("Object with {slug_name}={value} does not exist."),
          'invalid': _('Invalid value.'),
      }
  
      def __init__(self, slug_field=None, **kwargs):
          assert slug_field is not None, 'The `slug_field` argument is required.'
          self.slug_field = slug_field
 
</s> remove         'required': _('This field is required.'),
        'no_match': _('Invalid hyperlink - No URL match'),
        'incorrect_match': _('Invalid hyperlink - Incorrect URL match.'),
        'does_not_exist': _('Invalid hyperlink - Object does not exist.'),
        'incorrect_type': _('Incorrect type. Expected URL string, received {data_type}.'),
 </s> add         'required': _("This field is required."),
        'no_match': _("Invalid hyperlink - No URL match."),
        'incorrect_match': _("Invalid hyperlink - Incorrect URL match."),
        'does_not_exist': _("Invalid hyperlink - Object does not exist."),
        'incorrect_type': _("Incorrect type. Expected URL string, received {data_type}."), </s> remove         'required': _('This field is required.'),
 </s> add         'required': _("This field is required."), </s> remove         'invalid': _('This value does not match the required pattern.')
 </s> add         'invalid': _("This value does not match the required pattern.") </s> remove         'incorrect_type': _('Incorrect type. Expected pk value, received {data_type}.'),
 </s> add         'incorrect_type': _("Incorrect type. Expected pk value, received {data_type}."), </s> remove         'not_a_list': _('Expected a list of items but got type `{input_type}`.')
 </s> add         'not_a_list': _("Expected a list of items but got type `{input_type}`.")
        'invalid': _("Invalid value."),
      """
  
      default_error_messages = {
          'does_not_exist': _("Object with {slug_name}={value} does not exist."),
        'invalid': _("Invalid value."),
      }
  
      def __init__(self, slug_field=None, **kwargs):
          assert slug_field is not None, 'The `slug_field` argument is required.'
          self.slug_field = slug_field
keep keep keep keep replace keep keep keep keep keep
 use double quotes for user visible strings; end user visible strings in full stops; add some missing translation tags 
rest_framework/relations.py