private static String validFunction( String string)
    {
    return
      GeneratorSet.ALL.equals( string)
      ? string
      : validIdentifier( string);
    }
private static String validFunction ( String string ) { return GeneratorSet . ALL . equals ( string ) ? string : validIdentifier ( string ) ; }
Reports a GeneratorSetException if the given string is not a valid function id. Otherwise, returns this string.