pub unsafe extern "C" fn us_create_loop(
    hint: *mut c_void,
    wakeup_cb: Option<unsafe extern "C" fn(loop_: *mut us_loop_t)>,
    pre_cb: Option<unsafe extern "C" fn(loop_: *mut us_loop_t)>,
    post_cb: Option<unsafe extern "C" fn(loop_: *mut us_loop_t)>,
    ext_size: c_uint
) -> *mut us_loop_t