def xorS(a, b):
 assert (len(a) == len(b))
 x = []
 for i in range(len(a)):
  x.append(chr((ord(a[i]) ^ ord(b[i]))))
 return ''.join(x)

def xorS ( a , b ) : assert ( len ( a ) == len ( b ) ) x = [ ] for i in range ( len ( a ) ) : x . append ( chr ( ( ord ( a [ i ] ) ^ ord ( b [ i ] ) ) ) ) return '' . join ( x )
xor two strings .