Class nightmare\designpattern\singleton

Located at designpattern/singleton.php

Methods
`public static`	`get_instance(): self` gets the instance via lazy initialization (created on first usage) gets the instance via lazy initialization (created on first usage)	#
`public`	`__wakeup()` prevent from being unserialized (which would create a second instance of it) prevent from being unserialized (which would create a second instance of it)	#