compound
\\[0ex]IsMonHom\{$M_{1}$,$M_{2}$\}($f$) $\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$FunThru2op($\mid$$M_{1}$$\mid$;$\mid$$M_{2}$$\mid$;$\ast$;$\ast$;$f$) \& $f$(e) = e