docs: def tokens(self, instance):
          """
          Just display current acceptable TOTP tokens
          """
          if not instance.pk:
              # e.g.: Use will create a new TOTP entry
              return "-"
  
          totp = TOTP(instance.bin_key, instance.step, instance.t0, instance.digits)
  
          tokens = []
          for offset in range(-instance.tolerance, instance.tolerance + 1):
              totp.drift = instance.drift + offset
              tokens.append(totp.token())
  
          return " ".join(["%s" % token for token in tokens])