flatten array function

flatten.py

def flatten( arr, arr2 ):
        for ele in enumerate( arr ):
                if type(ele[1]) is list:
                        flatten (ele[1], arr2)
                else:
                        z.append(ele[1])

y = [2,[3,[4,9]],4,[5,6]]

z = []
flatten(y,z)
print (y)
print "becomes"
print (z)