Return the first position of substr in str[start:end] using the
given search direction or -1 if not found. -2 is returned in case
an error occurred and an exception is set.
Py_ssize_tPyUnicode_Find(PyObject* str, PyObject* substr, Py_ssize_t start, Py_ssize_t end, int direction)
Return the first position of substr in str[start:end] using the given search direction or -1 if not found. -2 is returned in case an error occurred and an exception is set.