Join two 2D numpy array with one row over another

Two numpy arrays, lets say

a = np.array([[1,2], [3,4]])
b = np.array([[5,6], [7,8]])

I would like to combine two arrays into one single array such that the results looks like below array

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

I tried using concatenate, merge function, but cannot able to find pythonic way to solve this.
Is there is any in built function to solve my problem.

>Solution :

IIUC, you could stack, swap the axes, and reshape:

np.stack([a,b]).swapaxes(0,1).reshape((-1,2))

Or use np.c_ and reshape:

np.c_[a,b].reshape((-1,2))

Output:

array([[1, 2],
       [5, 6],
       [3, 4],
       [7, 8]])