https://docs.python.org/3/c-api/tuple.html#c.PyTuple_GetSlice

In the c-api it says (emphasis mine):

    PyObject* PyTuple_GetSlice(PyObject *p, Py_ssize_t low, Py_ssize_t high)¶
    Return value: New reference.

Take a slice of the tuple pointed to by p from low to high and return it **as a new tuple**.

But when slicing the entire tuple, CPython will return already existing instance, not a new tuple.

https://github.com/python/cpython/blob/3.8/Objects/tupleobject.c#L448-L451

I propose the language in the docs be loosened so as not to tie the hands of implementation

Verified from Python.
>>> t = (1,2,3)
>>> t2 = t[:]
>>> id(t), id(t2)
(1672756229504, 1672756229504)

A partial slice cannot the original tuple, so I presume that the emphasis is about returning a (new) *tuple*, rather than some sort of view of the original.  However,
        Py_INCREF(a);
        return (PyObject *)a;
date back to at least 1997 (GvR), so the optimization is not new.  I don't know what should replace 'New reference.'  'Old or new reverence.'?

"Take a slice of the tuple pointed to by p from low to high and return it **as a new tuple**."

could be replaces with

"Return the slice of the tuple point to by p for low to high. If it is a proper subslice, return a new tuple."

This leave it undefined when a complete slice.

The part about "new tuple" can be removed. The documentation olready contains an automatically generated note about a new reference.

PR 16925 improves the documentation for getting/setting items/slices of lists and tuples.

New changeset d898d20 by Serhiy Storchaka in branch 'master':
bpo-38557: Improve documentation for list and tuple C API. (GH-16925)
d898d20

New changeset 7356e10 by Miss Skeleton (bot) in branch '2.7':
bpo-38557: Improve documentation for list and tuple C API. (GH-16925)
7356e10

New changeset 334fc92 by Miss Skeleton (bot) in branch '3.7':
bpo-38557: Improve documentation for list and tuple C API. (GH-16925)
334fc92

New changeset 4992dc6 by Miss Skeleton (bot) in branch '3.8':
bpo-38557: Improve documentation for list and tuple C API. (GH-16925)
4992dc6