getLastSignal :: SignalList -> Maybe Signal
getLastSignal signals@(CSignalList (_:_)) = Just $ last sigList 
  where sigList = signalList signals
getLastSignal :: SignalList -> Maybe Signal
getLastSignal signals@(CSignalList (_:_)) = Just $ last sigList 
  where sigList = signalList signals
getLastSignal signals@(CSignalList (_:_)) = Just $ last sigList 
  where sigList = signalList signals