\[\mathscr{M}\mskip-3.0muI\mskip 3.0mu\left(z\right)=\mathscr{M}\mskip-3.0muf%
\mskip 3.0mu\left(1-z\right)\mathscr{M}\mskip-3.0muh\mskip 3.0mu\left(z\right).\]