pub unsafe extern "C" fn fdb_future_set_callback(
f: *mut FDBFuture,
callback: FDBCallback,
callback_parameter: *mut c_void,
) -> fdb_error_t
pub unsafe extern "C" fn fdb_future_set_callback(
f: *mut FDBFuture,
callback: FDBCallback,
callback_parameter: *mut c_void,
) -> fdb_error_t