/**
   * SimpleCalc Parse method for A -> P { '+' P }
   **/

  Object A()
    {
    Object result = P();                        // get first addend
    if( isFailure(result) ) return failure;

    while( skipWhitespace() && nextCharIs('+') )
      {
      Object P2 = P();                          // get next addend
      if( isFailure(P2) ) return failure;
      try
        {
        result = Arith.add(result, P2);        // accumulate result
        }
      catch( IllegalArgumentException e )
        {
        System.err.println("error: IllegalArgumentException caught");
        }
      }
    return result;
    }