def _angle(self, a=0.0):
    angle = (Math.atan2(self.dy, self.dx) + a)
    while (angle > (2 * Math.PI)):
        angle = (angle - (2 * Math.PI))
    while (angle < 0):
        angle = (angle + (2 * Math.PI))
    return angle
def _angle(self, a=0.0):
    angle = (Math.atan2(self.dy, self.dx) + a)
    while (angle > (2 * Math.PI)):
        angle = (angle - (2 * Math.PI))
    while (angle < 0):
        angle = (angle + (2 * Math.PI))
    return angle