bp_groups_set_group_type( int $group_id, string|array $group_type, bool $append = false )

function bp_groups_set_group_type( $group_id, $group_type, $append = false ) {
	// Pass an empty group type to remove group's type.
	if ( ! empty( $group_type ) && is_string( $group_type ) && ! bp_groups_get_group_type_object( $group_type ) ) {
		return false;
	}

	// Cast as array.
	$group_type = (array) $group_type;

	// Validate group types.
	foreach ( $group_type as $type ) {
		// Remove any invalid group types.
		if ( is_null( bp_groups_get_group_type_object( $type ) ) ) {
			unset( $group_type[ $type ] );
		}
	}

	$retval = bp_set_object_terms( $group_id, $group_type, 'bp_group_type', $append );

	// Bust the cache if the type has been updated.
	if ( ! is_wp_error( $retval ) ) {
		wp_cache_delete( $group_id, 'bp_groups_group_type' );

		/**
		 * Fires just after a group type has been changed.
		 *
		 * @since BuddyPress 2.6.0
		 *
		 * @param int          $group_id   ID of the group whose group type has been updated.
		 * @param string|array $group_type Group type or array of group types.
		 * @param bool         $append     Whether the type is being appended to existing types.
		 */
		do_action( 'bp_groups_set_group_type', $group_id, $group_type, $append );
	}

	return $retval;
}