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typedef JsonReader<1024*2> JsonReader2k;
// ...
File file = SD.open("/data.json", FILE_READ);
  if (!file) {
    Serial.println(F("/data.json not found or could not be opened"));
    while (true); // halt
  }
  JsonReader2k jsonReader;
  jsonReader.begin(file);
  while(jsonReader.read()) {
    switch(jsonReader.nodeType()) {
      case JsonReader2k::Value:
        Serial.print("Value ");
        Serial.println(jsonReader.rawValue());
        break;
      case JsonReader2k::Key:
        Serial.print("Key ");
        Serial.println(jsonReader.rawValue());
        break;
      case JsonReader2k::Object:
        Serial.println("Object");
        break;
      case JsonReader2k::EndObject:
        Serial.println("End Object");
        break;
      case JsonReader2k::Array:
        Serial.println("Array");
        break;
      case JsonReader2k::EndArray:
        Serial.println("End Array");
        break;
      case JsonReader2k::Error:
        Serial.println("Error!");
        break;
    }
  }
  file.close();