Source

File: wp-includes/class-wp-admin-bar.php

final protected function _get_node( $id ) {
		if ( $this->bound ) {
			return;
		}

		if ( empty( $id ) ) {
			$id = 'root';
		}

		if ( isset( $this->nodes[ $id ] ) ) {
			return $this->nodes[ $id ];
		}
	}