Python: calling a class/method with parenthesis vs. no-parenthesis? whats the diff?

calling a class/method with parenthesis vs. no-parenthesis? whats the diff?

>>> class Service:

secret = "He is a alian."

def setname(self, name):

self.name=name

def sum(self,a,b):

print "{}, {}+{} = {}".format(self.name,a,b,a+b)

code source: https://wikidocs.net/28

aman = Service()

awoman = Service

>>> type(aman)

<type 'instance'>

>>> type(awoman)

<type 'classobj'>

>>> 

classobj can assign a instance.

>>> kim=awoman()

>>> type(kim)

<type 'instance'>

>>> aman.setname("Strong")

>>> awoman.setname("Beauty")

Traceback (most recent call last):

  File "<pyshell#58>", line 1, in <module>

    awoman.setname("Beauty")

TypeError: unbound method setname() must be called with Service instance as first argument (got str instance instead)

>>>