'Distance away from home, in meters. Returns 3D distance if `down` is known, otherwise 2D distance.'

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)))
