how to append a numpy array to another code example

Example 1: np append row

A= [[1, 2, 3], [4, 5, 6]]
np.append(A, [[7, 8, 9]], axis=0)

    >> array([[1, 2, 3],
              [4, 5, 6],
              [7, 8, 9]])
#or 
np.r_[A,[[7,8,9]]]

Example 2: numpy python add array

x1 = [1, 2]
x2 = [1, 2]
print(np.add(x1, x2))
# [2, 4]