Learns the sum of two numbers. In response to an hn comment.

learn_sum.py

import numpy as np

X = np.array([
                [1, 4],
                [20, 35],
                [8, 15]
             ])
y = np.array([3, 15, 7])

opt_theta = np.linalg.lstsq(X, y)

print(opt_theta[0])
# Prints [-1. 1.]