pub unsafe extern "C" fn coap_persist_track_funcs(
context: *mut coap_context_t,
observe_added: coap_observe_added_t,
observe_deleted: coap_observe_deleted_t,
track_observe_value: coap_track_observe_value_t,
dyn_resource_added: coap_dyn_resource_added_t,
resource_deleted: coap_resource_deleted_t,
save_freq: u32,
user_data: *mut c_void,
)