\item The \module{itertools} module gained a

\function{groupby(\var{iterable}\optional{, \var{func}})} function,

inspired by the GROUP BY clause from SQL.

\var{iterable} returns a succession of elements, and the optional

\var{func} is a function that takes an element and returns a key

value; if omitted, the key is simply the element itself.

\function{groupby()} then groups the elements into subsequences

which have matching values of the key, and returns a series of 2-tuples

containing the key value and an iterator over the subsequence.

Here's an example. The \var{key} function simply returns whether a

number is even or odd, so the result of \function{groupby()} is to

return consecutive runs of odd or even numbers.

\begin{verbatim}

\end{verbatim}