'evaluate a point at t'

def point_at_t(self, t):

    one_minus_t_powers = np.power((1.0 - t), self._orders)[::(-1)]
    t_powers = np.power(t, self._orders)
    tt = (one_minus_t_powers * t_powers)
    _x = sum((tt * self._px))
    _y = sum((tt * self._py))
    return (_x, _y)
