code: function(filepath, callback) {
      jsonStr = this.parseFile(filepath);
      if(!jsonStr) {  
        process.stdout.write(filepath+' is not exist');
        throw new Error('file not exist');
        process.exit(1);
      }
      try {
        var sentences = jsonStr.sentences;
        var options = jsonStr.options;
        options.callback = callback;
        this.speak(sentences, options);
        return true;
      } catch(e) {
        throw new Error('error while speaking');
      }
    }
docs: read and say it from json file.
  json format :
  {
  "options": {
  "voice": <voice name>,
  "writetext": (default false) true to show tts text to the console or false to not shown the text
  },
  "sentences": <array of sentences list>
  }
  ex:
  {
  "options": {
  "voice": "vicki",
  "writetext": true
  },
  "sentences": [
  "Hello how are you today",
  "this system is using better-say",
  "for the current version, better-say is exclusive only for Mac OSX users"
  ]
  }
  @param String filepath a json file path