[Hook] Fix hook.

include/aidge/hook/Hook.hpp

@@ -31,11 +31,11 @@ protected:
 
 public:
     Hook(std::shared_ptr<Operator> op) : mOperator(op) {}
-    virtual ~Hook();
+    virtual ~Hook() = default;
 
     virtual void call() = 0;
 
 };
 }
 
-#endif /* Hook_H_ */
\ No newline at end of file
+#endif /* Hook_H_ */

python_binding/operator/pybind_Operator.cpp

@@ -20,6 +20,7 @@ void init_Operator(py::module& m){
     py::class_<Operator, std::shared_ptr<Operator>>(m, "Operator")
     .def("output", &Operator::output, py::arg("outputIdx"))
     .def("input", &Operator::input, py::arg("inputIdx"))
+    .def("nb_data_inputs", &Operator::nbDataInputs)
     .def("associate_input", &Operator::associateInput, py::arg("inputIdx"), py::arg("data"))
     .def("set_datatype", &Operator::setDatatype, py::arg("datatype"))
     .def("set_backend", &Operator::setBackend, py::arg("name"))