Function: Generates a random UUID (version 4).

Function: Checks whether a user is still logged in, for the heartbeat.

Function: Returns RegEx body to liberally match an opening HTML tag.

Function: Retrieves a canonical form of the provided charset appropriate for passing to PHP functions such as htmlspecialchars() and charset HTML attributes.

Function: Sets the mbstring internal encoding to a binary safe encoding when func_overload is enabled.

Function: Resets the mbstring internal encoding to a users previously set encoding.

Function: Filters/validates a variable as a boolean.

Function: Deletes a file.