以下是核心编程中一个stack的例子：

'''
Created on 2012-3-6

@author: Administrator
'''
#!/usr/bin/env python

stack=[]

def pushit():
    stack.append(raw_input('Enter new String').strip())
    
    
def popit():
    if len(stack)==0:
        print 'has empty!'
    else:
        print 'remove [', stack.pop() ,']'
        

def viewstack():
    print stack
    
CMDs = {'u':pushit,'o':popit,'v':viewstack}

def showmenu():
    pr="""
    p(U)sh
    p(O)p
    (V)iew
    (Q)uit
    
    Enter choice : """
    
    while True:
        while True:
            try:
                choice = raw_input(pr).strip()[0].lower()
            except (EOFError,KeyboardInterrupt,IndexError):
                choice = 'q'        
            print '\nYou picked:[%s]' % choice
            if choice not in 'uovq':
                print 'Invalid option,try again'
            else:
                break
        
        if choice =='q':
            break
        CMDs[choice]()
        
if __name__=='__main__':
    showmenu()