does sleep have to be imported in python code example

Example 1: sleep in python 3

#!/usr/bin/python3
import time

print ("Start : %s" % time.ctime())
time.sleep( 5 )
print ("End : %s" % time.ctime())

# Start : Mon Feb 15 12:08:42 2016
# End : Mon Feb 15 12:08:47 2016

Example 2: python sleep

import time

start = time.time()
print("sleeping...")
time.sleep(0.5)
print("woke up...")
elapsed_time = time.time() - start

print("elapsed time:", elapsed_time * 1000, "milliseconds")