Generate a unit vector (norm = 1)

def unit_vector(self):
        """Generate a unit vector (norm = 1)"""
        x = -math.cos(self.rpitch) * math.sin(self.ryaw)
        y = -math.sin(self.rpitch)
        z = math.cos(self.rpitch) * math.cos(self.ryaw)
        return Vector3(x, y, z)