Copyright (c) 2012-2022 by Martin Scharrer [email protected]
CTAN: https://www.ctan.org/pkg/multienv
Code repository: https://github.com/MartinScharrer/multienv/

This package provides a multienv environment which allows to easily add multiple environments using a key=value syntax. Macros to define environments using this syntax are also provided.

The following 'multienv' environment:

\begin{multienv}{enva,envb=arg,add code={code before}{code after},
    envc=[oarg]{marg}}
  content
\end{multienv}

is basically identical to:

\begin{enva}
  \begin{envb}{arg}
    code before
    \begin{enc}[oarg]{marg}
      content
    \end{enc}
    code after
  \end{envb}
\end{enva}

except that actually the "plain" form together with explicit groups is used: \begingroup\enva .. \endenva\endgroup.