import numpy
f=lambda M:map(M[::-1].diagonal,range(1-len(M),len(M[0])))

for M in [[1]], [[1,2],[3,4]], [[1,2,3],[4,5,6]], [[11,2,5],[3,99,3],[4,8,15],[16,23,42]]:
	print(list(f(numpy.array(M))))