\def\havemjocommon{1}
-% Needed for \mathbb.
-\usepackage{amsfonts}
+\ifx\mathbb\undefined
+ \usepackage{amsfonts}
+\fi
-% Needed for \bigtimes.
-\usepackage{mathtools}
+\ifx\bigtimes\undefined
+ \usepackage{mathtools}
+\fi
% Place the argument in matching left/right parentheses.
\newcommand*{\of}[1]{ \left({#1}\right) }