gh-125916: Adapt functools.reduce() to Argument Clinic

Modules/_functoolsmodule.c

@@ -933,28 +933,27 @@ _functools_cmp_to_key_impl(PyObject *module, PyObject *mycmp)
 /* reduce (used to be a builtin) ********************************************/
 
 /*[clinic input]
-@text_signature "($module, function, iterable[, initial], /)"
 _functools.reduce
 
     function as func: object
     iterable as seq: object
     initial as result: object = NULL
     /
 
-Apply a function of two arguments cumulatively to an iterable, from left to right.
+Apply a function of two arguments cumulatively to the items of an iterable, from left to right.
 
-This efficiently reduces the iterable to a single value.  If initial is present,
+This effectively reduces the iterable to a single value.  If initial is present,
 it is placed before the items of the iterable in the calculation, and serves as
 a default when the iterable is empty.
 
 For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5])
-calculates ((((1 + 2) + 3) + 4) + 5).
+calculates ((((1 + 2) + 3) + 4) + 5).")
 [clinic start generated code]*/
 
 static PyObject *
 _functools_reduce_impl(PyObject *module, PyObject *func, PyObject *seq,
                        PyObject *result)
-/*[clinic end generated code: output=30d898fe1267c79d input=d85ca22bf7ee578b]*/
+/*[clinic end generated code: output=30d898fe1267c79d input=cadc408bded707d1]*/
 {
     PyObject *args, *it;