In [1]: import numpy as np
In [2]: a = np.ndarray((3, 2, 3))
In [3]: b = np.ndarray((2, 2, 3))
In [4]: print(a.shape, b.shape)
(3, 2, 3) (2, 2, 3)
In [5]: c = np.concatenate((a, b), axis = 0)
In [6]: print(c.shape)
(5, 2, 3)
In [7]: 

In [2]: import numpy as np
In [3]: a = np.array([1, 2, 3, 4, 5])
In [4]: a = np.append(a, 10)
In [5]: a
Out[5]: array([ 1, 2, 3, 4, 5, 10])
In [6]: a = np.append(a, [1, 2, 3])
In [7]: a
Out[7]: array([ 1, 2, 3, 4, 5, 10, 1, 2, 3])

In [9]: a = [1, 2, 3, 4]
In [10]: b = [5, 6, 7, 8]
In [11]: a
Out[11]: [1, 2, 3, 4]
In [12]: b
Out[12]: [5, 6, 7, 8]
In [13]: c = a.extend(b)
In [14]: c
In [15]: a
Out[15]: [1, 2, 3, 4, 5, 6, 7, 8]

In [28]: a = [1, 2,3,4]
In [29]: a.append(6)
In [30]: a
Out[30]: [1, 2, 3, 4, 6]
In [31]: