Example of a module proxy which selectively overrides behaviour of specific functions.

gistfile1.py

from __future__ import print_function

import wrapt
import time
import sys

class TimeModuleProxy(wrapt.ObjectProxy):

    def __init__(self, module=time):
        super(TimeModuleProxy, self).__init__(module)

    def sleep(self, seconds):
        print('I am going to sleep for %ss.' % seconds)
        return self._self_wrapped.sleep(seconds)

sys.modules['wrapt_time'] = TimeModuleProxy()

from wrapt_time import sleep, asctime, tzname

print(tzname)
print(asctime())

sleep(10)