Use of own operator declarations

[math@…]

I need often own operators hence I use

\DeclareMathOperator*{\mean}{mean}
...
\[
 \mean\limits_{x \in X} ...
\]

This won't work with this plugin, since I declare the operator in the preamble. Is it possible to parse the text while using a separator for preamble and content? e.g.

{{{
#!Latex
\DeclareMathOperator*{\mean}{mean}
----
\[
 \mean\limits_{x \in X} ...
\]
}}}