docs: def get_field(self, field_name, args, kwargs):
          """Create a special value when field missing and tolerant."""
          try:
              obj, arg_used = super(FormatterWrapper, self).get_field(
                      field_name, args, kwargs)
          except (KeyError, IndexError, AttributeError):
              if not self.tolerant:
                  raise
  
              obj = MissingField(field_name)
              arg_used = field_name
  
          return obj, arg_used