public static extern void pa_operation_set_state_callback(pa_operation *o, [NativeTypeName("pa_operation_notify_cb_t")] delegate *unmanaged <pa_operation *, void *, void> cb, void *userdata);
 public static extern pa_operation_state_t pa_operation_get_state([NativeTypeName("const pa_operation *")] pa_operation *o);
 public static extern void pa_operation_unref(pa_operation *o);
 public static extern void pa_operation_cancel(pa_operation *o);
 public static extern pa_operation *pa_operation_ref(pa_operation *o);