def _strxor(s1, s2):
 return ''.join(map((lambda x, y: chr((ord(x) ^ ord(y)))), s1, s2))

def _strxor ( s1 , s2 ) : return '' . join ( map ( ( lambda x , y : chr ( ( ord ( x ) ^ ord ( y ) ) ) ) , s1 , s2 ) )
utility method .