var stringifyJSON = function(obj) {
  //return string of object
  //lets test to make sure obj is an array
  var result = '';

  if (Array.isArray(obj)) {
    result += '[';
    for (var i = 0; i < obj.length; i++) {
      if (i !== obj.length - 1) {
        result += obj[i].toString() + ',';
      } else {
        result += obj[i].toString();
      }
    }
    result += ']';
  } else if (typeof obj === 'object' && !Object.is(obj, null)) {
    var objectKeys = Object.keys(obj);
    //console.log(notLastArgument);
    result += '{';
    for (var i = 0; i < objectKeys.length; i++) {
      if (i !== objectKeys.length - 1) {
        result += '"' + objectKeys[i] + '"' + ':' + '"' + obj[objectKeys[i]] + '"' + ',';
      } else {
        result += '"' + objectKeys[i] + '"' + ':' + '"' + obj[objectKeys[i]] + '"';
      }

      //console.log(result);
    }
    result += '}';
  } else if (typeof obj === 'function' || typeof obj === 'undefined') {
    return undefined;
  } else if (!Object.is(obj, null) && (typeof obj === 'number' || typeof obj === 'string')) {
    return obj.toString();
  } else {
    return 'null';
  }

   //add a way to stringify null and numbers and a string



  return result;
};