The "Cannot make a static reference to the non-static method" error occurs when you try to call a non-static method from a static context.
In Python, @classmethod is a decorator that is used to define a method as a class method.
In Python, a static method is a method that belongs to a class rather than an instance of the class.
Using $this inside a static function is not allowed in PHP because the $this variable is only available within the context of a non-static method.
In Java, static methods are methods that belong to a class rather than an instance of the class. They can be called without creating an instance of the class, using the name of the class and the dot operator (.).