Concatenate two numpy arrays in the 4th dimension

Question

I got two numpy arrays in three dimensions. I need it to concatendate it with other numpy array so that the resulting array has four dimensions. In Matlab, this can be performed via cat(4,a,b), but how to do the same using numpy in python.

Like

a = one((1,2,3))
b = one ((1,2,3))
c= concatenate((a,b), axis=3)

Just to clarify, I want c[:,:,:,0] and c[:,:,:,1] to correspond with the a and b.