Python Static Method

How to define a static method in Python?Demo:

#!/usr/bin/python2.7
#coding:utf-8
# FileName: test.py
# Author: lxw
# Date: 2015-07-03

#Inside a class, we can define attributes and methods
class Robot:
    '''Robot class.

    Attributes and Methods'''
    population = 0
    def __init__(self, name):
        self.name = name
        Robot.population += 1
        print('(Initialize {0})'.format(self.name))

    def __del__(self):
        Robot.population -= 1
        if Robot.population == 0:
            print('{0} was the last one.'.format(self.name))
        else:
            print('There are still {0:d} robots working.'.format(Robot.population))

    def sayHi(self):
        print('Greetings, my master call me {0}.'.format(self.name))

    '''
    #The following class method is OK.
    @classmethod
    def howMany(cls):   #cls is essential.
        print('We have {0:d} robots.'.format(cls.population))
    '''

    '''
    #The following static method is OK.
    @staticmethod
    def howMany():
        print('We have {0:d} robots.'.format(Robot.population))
    '''

    #The following class method is OK.
    def howMany(cls):   #cls is essential.
        print('We have {0:d} robots.'.format(cls.population))
    howMany = classmethod(howMany)

    '''
    #The following static method is OK.
    def howMany():
        print('We have {0:d} robots.'.format(Robot.population))
    howMany = staticmethod(howMany)
    '''
    

def main():
    robot1 = Robot("lxw1")
    robot1.sayHi()
    #staticmethod/classmethod           ，          ，  classmethod      cls  
    Robot.howMany()
    robot1.howMany()
    
    robot2 = Robot("lxw2")
    robot2.sayHi()
    Robot.howMany()
    robot2.howMany()

if __name__ == '__main__':
    main()
else:
    print("Being imported as a module.")

Differences between staticmethod and classmethod:
classmethod:
Its definition is mutable via inheritance, Its definition follows subclass, not parent class, via inheritance, can be
overridden by subclass. It is important when you want to write a factory method and by this custom attribute(s)
can be attached in a class.
staticmethod:
Its definition is immutable via inheritance. 他の言語のstaticメソッドと似ています.