wikimedia / mediawiki

		// Move some keys to the top

		$out = [];

		foreach ( $this->promote as $key ) {

			if ( isset( $this->json[$key] ) ) {

				$out[$key] = $this->json[$key];

				unset( $this->json[$key] );

			}

		}

		$out += $this->json;

		// Put this at the bottom

	 * @return mixed Old value if one was present, null otherwise

	 */

	public function unsetVal( $key ) {

		if ( !isset( $this->data[$key] ) ) {

			$ret = null;

		} else {

			$ret = $this->data[$key];

			unset( $this->data[$key] );

		}

		return $ret;

	}