Verifies that constraint is satisfied.

    flags library calls this method to verify Validator's constraint.

    Args:
      flag_values: flags.FlagValues, the FlagValues instance to get flags from.
    Raises:
      Error: Raised if constraint is not satisfied.

def verify(self, flag_values):
    """Verifies that constraint is satisfied.

    flags library calls this method to verify Validator's constraint.

    Args:
      flag_values: flags.FlagValues, the FlagValues instance to get flags from.
    Raises:
      Error: Raised if constraint is not satisfied.
    """
    param = self._get_input_to_checker_function(flag_values)
    if not self.checker(param):
      raise _exceptions.ValidationError(self.message)