code: func (t *tree) parseQuotedExpr(str string) ast.Node {
  	var tt = &tree{lex: lexExpr("", str)}
  	defer tt.lex.drain()
  	return tt.parseExpr(0)
  }
docs: // parseQuotedExpr ignores the current lex/parse state and parses the given
  // string as a standalone expression.