function is_protected_meta( $meta_key, $meta_type = null ) {
	$protected = ( '_' == $meta_key[0] );

	/**
	 * Filters whether a meta key is considered protected.
	 *
	 * @since 3.2.0
	 *
	 * @param bool        $protected Whether the key is considered protected.
	 * @param string      $meta_key  Meta key.
	 * @param string|null $meta_type Type of object metadata is for (e.g., comment, post, term, or user).
	 */
	return apply_filters( 'is_protected_meta', $protected, $meta_key, $meta_type );
}