gistfile1.py

import re

class CapsTalk(object):
    def __init__(self):
        self.parseInput()
    
    def parseInput(self):
        counter = 0
        
        while True:
            ip = raw_input('> ')
            
            out = ""
            
            ip = re.sub(r'[^a-zA-Z0-9]', '', ip)
            
            for i in range(0,len(ip)):
                if counter%2 == 0:
                    out += ip[i].lower()
                else:
                    out += ip[i].upper()
                
                counter += 1
            
            print out
            
            #If counter is even it can be reset
            if counter%2 == 0:
                counter = 0

if __name__ == '__main__':
    CapsTalk()