delete $ibx->{mm};
is_deeply([ $ibx->mm->minmax ], $minmax, 'minmax unchanged');
is($ibx->mm->num_highwater, 10, 'num_highwater as expected');
delete $ibx->{mm};
is_deeply([ $ibx->mm->minmax ], $minmax, 'minmax unchanged');
is($ibx->mm->num_highwater, 10, 'num_highwater as expected');