code: public byte[] getBytes(int key) {
          PebbleTuple tuple = getTuple(key, PebbleTuple.TupleType.BYTES);
          if (tuple == null) {
              return null;
          }
          return (byte[]) tuple.value;
      }
docs: Returns the byte array to which the specified key is mapped, or null if the key does not exist in this
  dictionary.
  
  @param key
  key whose associated value is to be returned
  
  @return value to which the specified key is mapped