Function PyUnicode_CopyCharacters

pub unsafe extern "C" fn PyUnicode_CopyCharacters(
    to: *mut PyObject,
    to_start: Py_ssize_t,
    from: *mut PyObject,
    from_start: Py_ssize_t,
    how_many: Py_ssize_t,
) -> Py_ssize_t

Available on non-Py_LIMITED_API and non-PyPy only.