code: def light_travel_time_to_detector(self, det):
          
          d = self.location - det.location
          return float(d.dot(d)**0.5 / constants.c.value)
docs: Return the light travel time from this detector
  
          Parameters
          ----------
          det: Detector
              The other detector to determine the light travel time to.
  
          Returns
          -------
          time: float
              The light travel time in seconds