Function usleep 

#[unsafe(no_mangle)]
pub extern "C" fn usleep(useconds: useconds_t) -> c_int

👎Deprecated

See https://pubs.opengroup.org/onlinepubs/009695399/functions/usleep.html.

Deprecation

The usleep() function was marked obsolescent in the Open Group Base Specifications Issue 6, and removed in Issue 7.