code: def unmarshal(self, v):
          
          if not isinstance(v, timedelta):
              v = timedelta(seconds=v)
          return v
docs: Convert the value from parsed JSON structure to native python representation.
  
          By default this will leave the value as-is since the JSON parsing routines
          typically convert to native types. The exception may be date strings or other
          more complex types, where subclasses will override this behavior.