\cdbalgorithm{numerical\_flatten}{}

Move numerical factors out of operators whenever possible. This is
mostly useful in combination with derivative operators, as in the
example below.
\begin{screen}{1,2,3}
\partial{#}::PartialDerivative.
3 A \partial{4 B};
@numerical_flatten!(%);
12 A \partial{B};
\end{screen}
In contrast, the \subscommand{unwrap} algorithm moves non-numerical
factors out of derivative operators.

Objects to which this algorithm applies should carry
the \subsprop{NumericalFlat} property (which the \subsprop{Derivative}
objects inherit automatically).

\cdbseeprop{NumericalFlat}
\cdbseealgo{listflatten}
\cdbseealgo{sumflatten}
\cdbseealgo{unwrap}
