pub unsafe extern "C" fn coap_cancel_observe(
session: *mut coap_session_t,
token: *mut coap_binary_t,
message_type: coap_pdu_type_t,
) -> c_intpub unsafe extern "C" fn coap_cancel_observe(
session: *mut coap_session_t,
token: *mut coap_binary_t,
message_type: coap_pdu_type_t,
) -> c_int