in python xthe language has dropped the notion of unbound methods what we describe as an unbound method here is treated as simple function in for most purposesthis makes no difference to your codeeither wayan instance will be passed to method' first argument when it' called through an instance programs that do explicit type testing might be impactedthough--if you print the type of an instance-less class-level methodit displays "unbound methodin xand "functionin moreoverin it is ok to call method without an instanceas long as the method does not expect one and you call it only through the class and never through an instance that ispython will pass along an instance to methods only for through-instance calls when calling through classyou must pass an instance manually only if the method expects onec:\codec:\python \python class selflessdef __init__(selfdata)self data data def selfless(arg arg )return arg arg def normal(selfarg arg )return self data arg arg selfless( normal( selfless normal( selfless selfless( simple function in instance expected when called instance passed to self automatically +( + self expected by methodpass manually no instanceworks in xfails in xthe last test in this fails in xbecause unbound methods require an instance to be passed by defaultit works in because such methods are treated as simple functions not requiring an instance although this removes some potential error trapping in (what if programmer accidentally forgets to pass an instance?)it allows class' methods to be used as simple functions as long as they are not passed and do not expect "selfinstance argument the following two calls still fail in both and xthough--the first (calling through an instanceautomatically passes an instance to method that does not expect onewhile the second (calling through classdoes not pass an instance to method that does expect one (error message text here is per ) selfless( typeerrorselfless(takes positional arguments but were given selfless normal( typeerrornormal(missing required positional argument'arg designing with classes