TypeCheck.cpp

  // Case 1: arg is a non-tuple sequence object
  if (PySequence_Check(arg) && !PyTuple_Check(arg)) return true;

#ifdef WITH_NUMPY
  // Case 2: arg is an nd-array with type integer or bool
  if (PyArray_Check(arg) && (PyArray_TYPE((PyArrayObject*)arg) == NPY_INT64 || PyArray_TYPE((PyArrayObject*)arg) == NPY_BOOL)) return true;
#endif

  // Case 3: arg is a tuple containing at least one sequence object, ndarray, or LongTensor
  if (PyTuple_Check(arg)) {
    for (Py_ssize_t i = 0; i < PyTuple_GET_SIZE(arg); ++i) {
      PyObject *item = PyTuple_GET_ITEM(arg, i);
      if (PySequence_Check(item)) {
        return true;
      }
#ifdef WITH_NUMPY
      if (PyArray_Check(item) && (PyArray_TYPE((PyArrayObject*)item) == NPY_INT64 || PyArray_TYPE((PyArrayObject*)item) == NPY_BOOL)) return true;
#endif
      if (THPIndexTensor_Check(item)) return true;
    }
  }