refactor: Update add() method to allow for multiple handlers
refactor: Update add() method to allow for multiple handlers

Add method can now accept a string of handlers to fire. Handlers
are fired in the sequence they are provided (i.e. from left to
right: "handler_1 handler_2 handler_3").

cgabriel5/snippets,cgabriel5/snippets,cgabriel5/snippets