pub unsafe extern "C" fn onig_scan(
reg: OnigRegex,
str_: *const OnigUChar,
end: *const OnigUChar,
region: *mut OnigRegion,
option: OnigOptionType,
scan_callback: Option<unsafe extern "C" fn(arg1: c_int, arg2: c_int, arg3: *mut OnigRegion, arg4: *mut c_void) -> c_int>,
callback_arg: *mut c_void
) -> c_int