#!/usr/local/bin/env python 
# list 
users = ['s1','s2','s3'] 
print(users)
l1 = []
# add users in an empty list  
l1.append('d1') 
l1.append('d2') 
l1.insert(2,'d3')
print(l1) 
l1.pop()
print(l1) 
l1.insert(2,'d3')
