diff -r c941a85f5169 Modules/_bisectmodule.c
--- a/Modules/_bisectmodule.c	Sun Nov 20 22:21:55 2016 +0100
+++ b/Modules/_bisectmodule.c	Sun Nov 20 22:25:18 2016 +0100
@@ -252,26 +252,43 @@
     return PyLong_FromSsize_t(index);
 }
 
+/*[clinic input]
+bisect.insort_left
+
+    a: 'O'
+      The list in which ``x`` will be inserted.
+    x: 'O'
+      The value to insert.
+    lo: 'n' = 0
+      Lower bound, defaults to 0.
+    hi: 'n' = -1
+      Upper bound, defaults to -1 (meaning ``len(a)``).
+
+Insert item x in list a, and keep it sorted assuming a is sorted.
+
+If x is already in a, insert it to the left of the leftmost x.
+
+Optional args lo (default 0) and hi (default len(a)) bound the
+slice of a to be searched.
+
+[clinic start generated code]*/
+
 static PyObject *
-insort_left(PyObject *self, PyObject *args, PyObject *kw)
+bisect_insort_left_impl(PyObject *module, PyObject *a, PyObject *x,
+                        Py_ssize_t lo, Py_ssize_t hi)
+/*[clinic end generated code: output=aa0228af6970ec52 input=aa95f626a96be30a]*/
 {
-    PyObject *list, *item, *result;
-    Py_ssize_t lo = 0;
-    Py_ssize_t hi = -1;
+    PyObject *result;
     Py_ssize_t index;
-    static char *keywords[] = {"a", "x", "lo", "hi", NULL};
 
-    if (!PyArg_ParseTupleAndKeywords(args, kw, "OO|nn:insort_left",
-        keywords, &list, &item, &lo, &hi))
-        return NULL;
-    index = internal_bisect_left(list, item, lo, hi);
+    index = internal_bisect_left(a, x, lo, hi);
     if (index < 0)
         return NULL;
-    if (PyList_CheckExact(list)) {
-        if (PyList_Insert(list, index, item) < 0)
+    if (PyList_CheckExact(a)) {
+        if (PyList_Insert(a, index, x) < 0)
             return NULL;
     } else {
-        result = _PyObject_CallMethodId(list, &PyId_insert, "nO", index, item);
+        result = _PyObject_CallMethodId(a, &PyId_insert, "nO", index, x);
         if (result == NULL)
             return NULL;
         Py_DECREF(result);
@@ -280,24 +297,13 @@
     Py_RETURN_NONE;
 }
 
-PyDoc_STRVAR(insort_left_doc,
-"insort_left(a, x[, lo[, hi]])\n\
-\n\
-Insert item x in list a, and keep it sorted assuming a is sorted.\n\
-\n\
-If x is already in a, insert it to the left of the leftmost x.\n\
-\n\
-Optional args lo (default 0) and hi (default len(a)) bound the\n\
-slice of a to be searched.\n");
-
 static PyMethodDef bisect_methods[] = {
     BISECT_BISECT_RIGHT_METHODDEF
     BISECT_BISECT_METHODDEF
     BISECT_INSORT_RIGHT_METHODDEF
     BISECT_INSORT_METHODDEF
     BISECT_BISECT_LEFT_METHODDEF
-    {"insort_left", (PyCFunction)insort_left,
-        METH_VARARGS|METH_KEYWORDS, insort_left_doc},
+    BISECT_INSORT_LEFT_METHODDEF
     {NULL, NULL} /* sentinel */
 };