var stringifyJSON = function(obj) {
  // your code goes here
  if (obj === null) {
  	return "".concat (obj);
  }
  if (Array.isArray (obj)) {
  	// if (obj.length === 1) {
  	//   return ''.concat (obj, ']');
  	// } else {
  	//   var result = ''.concat (obj.shift (), ', ', stringifyJSON (obj));
  	//   return result;
  	// }
  	var massiveString = "[";
  	for (var i = 0; i < obj.length; ++i) {
  	  if (i !== 0) {
  	    massiveString += ",";
  	  }
  		massiveString += stringifyJSON(obj[i]);
  	}
  	massiveString += "]";
  	return massiveString;
  	//return ''.concat('[', result, ']');
  }
  if (typeof obj === "object") {
  // 	var keys = Object.keys (obj);
  // 	if (keys.length === 0) {
  // 	  return "";
  // 	} else {
  // 	  var result = "".concat (keys[0], obj[keys[0]]);
  // 	  delete obj[keys[0]];
  // 	  result = "".concat (result, stringifyJSON (obj));
  // 	  return result;
  // 	}
    var massiveString = "{";
    var seenFirstKey = false;
  	for (var key in obj) {
  	  if (seenFirstKey) {
  	    massiveString += ",";
  	  } else {
  	    seenFirstKey = true;
  	  }
  	  var value = stringifyJSON(obj[key]);
  	  if (value !== "") massiveString += stringifyJSON(key) + ':' + stringifyJSON(obj[key]);
  	}
  	massiveString += "}";
  	return massiveString;
  }
  if (typeof obj === "") {
  	return "".concat("\"", obj, "\"");
  }
  if (obj === undefined || typeof obj === "function") {
  	return "";
  }
  if (typeof obj === "string") {
    return "\"" + obj + "\""
  }
  else {
  	return "".concat (obj);
  }
};