How do I select a window from a numpy array with periodic boundary conditions?

import numpy as np

A=np.arange(16).reshape((4,4))

def neighbors(arr,x,y,n=3):
    ''' Given a 2D-array, returns an nxn array whose "center" element is arr[x,y]'''
    arr=np.roll(np.roll(arr,shift=-x+1,axis=0),shift=-y+1,axis=1)
    return arr[:n,:n]

print(A)
# [[ 0  1  2  3]
#  [ 4  5  6  7]
#  [ 8  9 10 11]
#  [12 13 14 15]]

print(neighbors(A,0,0))
# [[15 12 13]
#  [ 3  0  1]
#  [ 7  4  5]]

print(neighbors(A,1,0))
# [[ 3  0  1]
#  [ 7  4  5]
#  [11  8  9]]