code: def get_rand_string(length=12, allowed_chars='0123456789abcdef'):
      
      if not using_sysrandom:
          # This is ugly, and a hack, but it makes things better than
          # the alternative of predictability. This re-seeds the PRNG
          # using a value that is hard for an attacker to predict, every
          # time a random string is required. This may change the
          # properties of the chosen random sequence slightly, but this
          # is better than absolute predictability.
          random.seed(
              hashlib.sha256(
                  ("%s%s" % (
                      random.getstate(),
                      time.time())).encode('utf-8')
              ).digest())
      return ''.join([random.choice(allowed_chars) for i in range(length)])
docs: Returns a securely generated random string. Taken from the Django project
  
      The default length of 12 with the a-z, A-Z, 0-9 character set returns
      a 71-bit value. log_2((26+26+10)^12) =~ 71 bits