Function pyo3::ffi::PySlice_GetIndicesEx

pub unsafe fn PySlice_GetIndicesEx(
    slice: *mut PyObject, 
    length: Py_ssize_t, 
    start: *mut Py_ssize_t, 
    stop: *mut Py_ssize_t, 
    step: *mut Py_ssize_t, 
    slicelength: *mut Py_ssize_t
) -> c_int

This is supported on Py_3_7 only.