\bifuncindex: Fix so entries combine correctly with those of the built-in

	functions section.

Doc/texinputs/python.sty

@@ -269,7 +269,7 @@
 \newcommand{\opindex}[1]{\indexii{operator}{#1@{\idxcode{#1}}}}
 \newcommand{\exindex}[1]{\indexii{exception}{#1@{\idxcode{#1}}}}
 \newcommand{\obindex}[1]{\indexii{object}{#1}}
-\newcommand{\bifuncindex}[1]{\index{#1@{\idxcode{#1()}} (built-in function)}}
+\newcommand{\bifuncindex}[1]{\withsubitem{(built-in function)}{\ttindex{#1()}}}
 
 % Add an index entry for a module
 \newcommand{\refmodule}[2]{\index{#1@{\idxcode{#1}} (#2module)}}