src/components/Frontend.php
public function register_handle( $handle = '' ) {

		$this->registered_handles[] = $handle;

		// Only call add_actions() the first time a handle is registered, as the actions will still be registered for
		// subsequent handles.
		if ( 1 === count( $this->registered_handles ) ) {
			$this->add_actions();
		}
	}
public function register_handle( $handle = '' ) {

		$this->registered_handles[] = $handle;

		// Only call add_actions() the first time a handle is registered, as the actions will still be registered for
		// subsequent handles.
		if ( 1 === count( $this->registered_handles ) ) {
			$this->add_actions();
		}
	}
Registers an instance handle.

@param string $handle The handle name.