resumed there when the next element is requested by calling the
\method{next()} method of the returned iterator.
+\index{generator expression}
+\item[generator expression]
+An expression that returns a generator. It looks like a normal expression
+followed by a \keyword{for} expression defining a loop variable, range, and
+an optional \keyword{if} expression. The combined expression generates
+values for an enclosing function:
+
+\begin{verbatim}
+>>> sum(i*i for i in range(10)) # sum of squares 0, 1, 4, ... 81
+285
+\end{verbatim}
+
\index{GIL}
\item[GIL]
See \emph{global interpreter lock}.