goxpath.go
func (xp XPathExec) ExecBool(t tree.Node, opts ...FuncOpts) (bool, error) {
	res, err := xp.Exec(t, opts...)
	if err != nil {
		return false, err
	}

	b, ok := res.(tree.IsBool)
	if !ok {
		return false, fmt.Errorf("Cannot convert result to a boolean")
	}

	return bool(b.Bool()), nil
}
func (xp XPathExec) ExecBool(t tree.Node, opts ...FuncOpts) (bool, error) {
	res, err := xp.Exec(t, opts...)
	if err != nil {
		return false, err
	}

	b, ok := res.(tree.IsBool)
	if !ok {
		return false, fmt.Errorf("Cannot convert result to a boolean")
	}

	return bool(b.Bool()), nil
}
//ExecBool is like Exec, except it will attempt to convert the result to its boolean value.