nesting := 0
	var tokens []Token
	for {
		tok := in.Stack.Next()
		if tok == scanner.EOF || tok == '\n' {
			in.Error("unterminated arg list invoking macro:", macro.name)
		}
		if nesting == 0 && (tok == ')' || tok == ',') {
			return tokens, tok
		}
		if tok == '(' {
			nesting++
		}
		if tok == ')' {
			nesting--
		}
		tokens = append(tokens, Make(tok, in.Stack.Text()))
	}
}