\cdbalgorithm{keep\_terms}{}

Keep the~$m$th to the~$n$th terms in a sum, dropping all others.
\begin{screen}{1,2,3}
A + B + C + D + E + F;
@keep_terms!(%){3}{5};
D + E + F;
\end{screen}
Note that counting starts from zero.

\cdbseealgo{keep_weight}
\cdbseealgo{take_match}
