## sleep

cpython's `time.sleep` calls `pysleep`:
https://github.com/python/cpython/blob/v3.8.5/Modules/timemodule.c#L338

`pysleep` calls `Sleep`, probably the one defined in `Modules/_tkinter.c`, with millisecond precision (rounding up):
https://github.com/python/cpython/blob/v3.8.5/Modules/timemodule.c#L1873

`Modules/_tkinter.c:Sleep` (https://github.com/python/cpython/blob/v3.8.5/Modules/_tkinter.c#L361):
```c
static void
Sleep(int milli)
{
    /* XXX Too bad if you don't have select(). */
    struct timeval t;
    t.tv_sec = milli/1000;
    t.tv_usec = (milli%1000) * 1000;
    select(0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &t);
}
```