def unpatch():
    """
    Unpatch any previously patched modules.
    This operation is idempotent.
    """
    _PATCHED_MODULES.discard('httplib')
    setattr(httplib, PATCH_FLAG, False)
    # _send_request encapsulates putrequest, putheader[s], and endheaders
    unwrap(httplib.HTTPConnection, '_send_request')
    unwrap(httplib.HTTPConnection, 'getresponse')
    unwrap(httplib.HTTPResponse, 'read')
Unpatch any previously patched modules.
    This operation is idempotent.