func (p *Pipe) One(result interface{}) error {
	iter := p.Iter()
	if iter.Next(result) {
		return nil
	}
	if err := iter.Err(); err != nil {
		return err
	}
	return ErrNotFound
}
func (p *Pipe) One(result interface{}) error {
	iter := p.Iter()
	if iter.Next(result) {
		return nil
	}
	if err := iter.Err(); err != nil {
		return err
	}
	return ErrNotFound
}
func ( p * Pipe ) One ( result interface { } ) error { iter := p . Iter ( ) if iter . Next ( result ) { return nil } if err := iter . Err ( ) ; err != nil { return err } return ErrNotFound }
// One executes the pipeline and unmarshals the first item from the
// result set into the result parameter.
// It returns ErrNotFound if no items are generated by the pipeline.
One executes the pipeline and unmarshals the first item from the result set into the result parameter . It returns ErrNotFound if no items are generated by the pipeline .