assertpmux - adds asserts for parallel muxes

    assertpmux [options] [selection]

This command adds asserts to the design that assert that all parallel muxes
($pmux cells) have a maximum of one of their inputs enable at any time.

    -noinit
        do not enforce the pmux condition during the init state

    -always
        usually the $pmux condition is only checked when the $pmux output
        is used by the mux tree it drives. this option will deactivate this
        additional constraint and check the $pmux condition always.