@Nullable
 private static ArrayList<String> getStringOrArray(String name, JsonObject object) {
   final JsonElement jsonElement = object.get(name);
   final ArrayList<String> strings = Lists.newArrayList();
   if (jsonElement == null) return null;
   if (jsonElement.isJsonArray()) {
     final JsonArray array = jsonElement.getAsJsonArray();
     for (JsonElement element : array) {
       strings.add(element.getAsString());
     }
   } else {
     strings.add(jsonElement.getAsString());
   }
   return strings;
 }
    @Override
    public IpnbCellRaw deserialize(
        JsonElement json, Type typeOfT, JsonDeserializationContext context)
        throws JsonParseException {
      final JsonObject object = json.getAsJsonObject();
      final IpnbCellRaw cellRaw = new IpnbCellRaw();
      final JsonElement cell_type = object.get("cell_type");
      if (cell_type != null) {
        cellRaw.cell_type = cell_type.getAsString();
      }
      final JsonElement count = object.get("execution_count");
      if (count != null) {
        cellRaw.execution_count = count.isJsonNull() ? null : count.getAsInt();
      }
      final JsonElement metadata = object.get("metadata");
      if (metadata != null) {
        cellRaw.metadata = gson.fromJson(metadata, Map.class);
      }
      final JsonElement level = object.get("level");
      if (level != null) {
        cellRaw.level = level.getAsInt();
      }

      final JsonElement outputsElement = object.get("outputs");
      if (outputsElement != null) {
        final JsonArray outputs = outputsElement.getAsJsonArray();
        cellRaw.outputs = Lists.newArrayList();
        for (JsonElement output : outputs) {
          cellRaw.outputs.add(gson.fromJson(output, CellOutputRaw.class));
        }
      }
      cellRaw.source = getStringOrArray("source", object);
      cellRaw.input = getStringOrArray("input", object);
      final JsonElement language = object.get("language");
      if (language != null) {
        cellRaw.language = language.getAsString();
      }
      final JsonElement number = object.get("prompt_number");
      if (number != null) {
        cellRaw.prompt_number = number.getAsInt();
      }
      return cellRaw;
    }