code: def distance_home(self):
          
  
          if self.north is not None and self.east is not None:
              if self.down is not None:
                  return math.sqrt(self.north**2 + self.east**2 + self.down**2)
              else:
                  return math.sqrt(self.north**2 + self.east**2)
docs: Distance away from home, in meters. Returns 3D distance if `down` is known, otherwise 2D distance.