public function parent() {
        $path = $this->path;

        array_pop($path);

        if (empty($path)) {
            throw new \RuntimeException("Can't get parent of root path");
        }

        return new static($path);
    }
public function parent() {
        $path = $this->path;

        array_pop($path);

        if (empty($path)) {
            throw new \RuntimeException("Can't get parent of root path");
        }

        return new static($path);
    }
public function parent ( ) { $ path = $ this -> path ; array_pop ( $ path ) ; if ( empty ( $ path ) ) { throw new \ RuntimeException ( "Can't get parent of root path" ) ; } return new static ( $ path ) ; }
pop off one level of the path and return the new path

@return BIP32Path
pop off one level of the path and return the new path