func (p *parser) parseExprList(lhs bool) (list []ast.Expr) {
	if p.trace {
		defer un(trace(p, "ExpressionList"))
	}

	list = append(list, p.parseExpr(lhs))
	for p.tok == token.COMMA {
		p.next()
		list = append(list, p.parseExpr(lhs))
	}

	return
}

func (p *parser) parseLhsList() []ast.Expr {
	list := p.parseExprList(true)
	switch p.tok {
	case token.DEFINE:

}

// ----------------------------------------------------------------------------
// Common productions

// If lhs is set, result list elements which are identifiers are not resolved.
func (p *parser) parseExprList() (list []ast.Expr) {
	if p.trace {
		defer un(trace(p, "ExpressionList"))
	}

	list = append(list, p.parseExpr())
	for p.tok == token.COMMA {
		p.next()
		list = append(list, p.parseExpr())
	}