Update Modules/_decimal/_decimal.c

Co-authored-by: Serhiy Storchaka <[email protected]>

Author: skirpichev

Modules/_decimal/_decimal.c

@@ -4136,7 +4136,8 @@ PyDec_AsFloat(PyObject *dec)
 /*[clinic input]
 _decimal.Decimal.__round__
 
-    ndigits: object(c_default="NULL") = None
+    ndigits: object = NULL
+    /
 
 Return the Integral closest to self, rounding half toward even.
 [clinic start generated code]*/