Source

File: wp-includes/class-wp-customize-setting.php

final protected function multidimensional_get( $root, $keys, $default = null ) {
		if ( empty( $keys ) ) { // If there are no keys, test the root.
			return isset( $root ) ? $root : $default;
		}

		$result = $this->multidimensional( $root, $keys );
		return isset( $result ) ? $result['node'][ $result['key'] ] : $default;
	}