np array append

import numpy as np
a = np.array([1, 2, 3])
newArray = np.append(a, [10, 11, 12])

>>> import numpy as np
>>> np.append([[0, 1, 2], [3, 4, 5]],[[6, 7, 8]], axis=0)
array([[0, 1, 2],
       [3, 4, 5],
       [6, 7, 8]])

>>> np.append([1, 2, 3], [[4, 5, 6], [7, 8, 9]])
array([1, 2, 3, ..., 7, 8, 9])

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