code: def serialize(self):
          
          return {"hstart": self.hstart, "mstart": self.mstart,
                  "hend": self.hend, "mend": self.mend,
                  "is_valid": self.is_valid}
docs: This function serialize into a simple dict object.
          It is used when transferring data to other daemons over the network (http)
  
          Here we directly return all attributes
  
          :return: json representation of a Timerange
          :rtype: dict