<pre>on goPrevious  if the number of marked cards > 0 then    if the optionKey is down then go to first marked card else go to previous marked card  else    if the optionKey is down then      if the shiftKey is down then        get max(1,the number of this card - 100)        go to card it      else        get max(1,the number of this card - 10)        go to card it      end if    else if the commandKey is down then go to first card of this bkgnd    else go to previous card  end ifend goPrevious</pre>