message: Bind "Bool" instead of "Mask" type
diff: void export_scalar(py::module &m) {
  py::module scalar = m.def_submodule("scalar");
  - scalar.attr("Mask") = py::handle((PyObject *) &PyBool_Type);
  + scalar.attr("Bool") = py::handle((PyObject *) &PyBool_Type);
  scalar.attr("Float32") = py::handle((PyObject *) &PyFloat_Type);
  scalar.attr("Float64") = py::handle((PyObject *) &PyFloat_Type);
  scalar.attr("Int32") = py::handle((PyObject *) &PyLong_Type);
  