function update( $key, $val = false ) {
			if ( ! is_array( $key ) ) {
				$key = array( $key => $val );
			}

			$is_updated = false;

			foreach ( $key as $k => $v ) {
				if ( $this->{$k} === $v ) {
					continue;
				}

				if ( ( is_string( $this->{$k} ) && is_numeric( $v ) ||
				       ( is_numeric( $this->{$k} ) && is_string( $v ) ) ) &&
				     $this->{$k} == $v
				) {
					continue;
				}

				// Update value.
				$this->{$k} = $v;

				$is_updated = true;
			}

			$this->_is_updated = $is_updated;

			return $is_updated;
		}