code: def lscmp(a, b):
      
      l = len
      return not sum(0 if x == y else 1 for x, y in zip(a, b)) and l(a) == l(b)
docs: Compares two strings in a cryptographically safe way:
          Runtime is not affected by length of common prefix, so this
          is helpful against timing attacks.
  
          ..
              from vital.security import lscmp
              lscmp("ringo", "starr")
              # -> False
              lscmp("ringo", "ringo")
              # -> True
          ..