3.5: The function now sleeps at least seconds even if the sleep is interrupted by a signal, except if the signal handler raises an exception (see PEP 475 for the rationale).
3.11: On Unix, the clock_nanosleep() and nanosleep() functions are now used if available. On Windows, a waitable timer is now used.
3.13: Raises an auditing event.
3.15: Accepts any real number, not only integer or float.