### Description ```python import numpy as np x1, x2, y = np.random.normal(size=(3, 1000, 1)) assert np.isclose(x1.T @ y + x2.T @ y, (x1 + x2).T @ y) %timeit x1.T @ y + x2.T @ y %timeit (x1 + x2).T @ y 1.86 μs ± 21.1 ns per loop (mean ± std. dev. of 7 runs, 1,000,000 loops each) 1.33 μs ± 13.9 ns per loop (mean ± std. dev. of 7 runs, 1,000,000 loops each) ``` Works with either shared y, or shared x.