code: def get_random_string(length=12,
                        allowed_chars='abcdefghijklmnopqrstuvwxyz'
                                      'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'):
      
      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%s' % (random.getstate(), time.time(), settings.SECRET_KEY)).encode()
              ).digest()
          )
          return ''.join(random.choice(allowed_chars) for i in range(length))
docs: Return a securely generated random string.
      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