if tok != '\n' {
		in.Error("syntax error in #undef for macro:", name)
	}
	delete(in.macros, name)
}

func (in *Input) Push(r TokenReader) {
	if len(in.tr) > 100 {
		in.Error("input recursion")
	}
	in.Stack.Push(r)
}

func (in *Input) Close() {