There’s no magic happening! __init__ methods work just like all others. You need to explicitly take all the arguments you need in the subclass initialiser, and pass them through to the superclass.
class Superclass(object):
def __init__(self, arg1, arg2, arg3):
#Initialise some variables
#Call some methods
class Subclass(Superclass):
def __init__(self, subclass_arg1, *args, **kwargs):
super(Subclass, self).__init__(*args, **kwargs)
#Call a subclass only method
When you call Subclass(arg1, arg2, arg3) Python will just call Subclass.__init__(<the instance>, arg1, arg2, arg3). It won’t magically try to match up some of the arguments to the superclass and some to the subclass.