function tweetThread(stringToTweet,delim,img,r){                                         //pass a string variable with additional option to parse (used for bookending tweets)
//////////////////////////Variables////////////////////////////////////////////////////////
  var ss = SpreadsheetApp.getActiveSpreadsheet();                                        //spreadsheet
  var twtMax = 280;                                                                      //Character limit for Twitter (variable in case it changes)
  var tweets = new Array(0);                                                             //create final array to populate with tweets
  var total = "";                                                                        //variable for 'total' tweet-length section if parsing is required
  var start = 0;                                                                         //starting character for .substring() function, default 0
  var excess = 0;                                                                        //number of characters to strip off of 'total' to remove split words at end of tweet
  var parsed = "";                                                                       //parsed tweet (total - excess) to add to tweets
  var url = "";                                                                          //parsed image URLs
  console.log("tweetThread initiated!");                                                 //log function initiation
  console.log("using params: "                                                           //log paramaters being passed through function
              + "|stringToTweet:" + stringToTweet
              + "|delim:" + delim
              + "|img:" + img);
//////////////////////////Length Check/////////////////////////////////////////////////////
  try {                                                                                  //Attempt to check string value for parsing needs
    if (stringToTweet == undefined) {throw "Undefined Value: 'stringToTweet'"};          //thrown when tweet string is undefined
    var thread = stringToTweet.split(delim);                                             //split initial string along provided delimeter
    console.log("Input Thread Length: " + thread.length);                                //log number of strings in thread
  } catch(e) {                                                                           //Catch thrown error
    console.log("Cannot Split Thread. Error: " + e);                                     //Log error
  }
  try {                                                                                  //attempt to evaluate parsed tweet thread
    if (thread == undefined) {throw "Undefined Value: 'thread'"};                        //thrown when thread value doesn't exist
    for (i in thread){                                                                   //for each string in thread...
      if (thread[i].length == 0) {throw "Invalid Value: thread[" + i + "]"};             //thrown when thread has string error
      console.log("Thread section characters: " + thread[i].length);                     //log string length
      if (thread[i].length > twtMax){                                                    //check thread[i] length
        console.log("Cannot Tweet! Too long! Parsing...");                               //if thread [i] too long for tweet, needs to be split
        start = 0;                                                                       //reset starting character for substring
//////////////////////////Parsing Loop/////////////////////////////////////////////////////
        while (start<thread[i].length) {                                                 //As long as the starting position is NOT at the end of thread[i]...
          total = thread[i].substring(start,start + twtMax);                             //full length of tweet
          excess = total.length - total.lastIndexOf(" ");                                //amount of characters to cut off of 'total' to get to a space (end of last full word)
          parsed = thread[i].substring(start,start + twtMax - excess);                   //new text of tweet-length string ending in full word
          start = start + parsed.length + 1;                                             //new start position is the first character after finished tweet
          tweets.push(parsed);                                                           //adds tweet to thread
          console.log("Parsed new tweet," + " length: " +
                      parsed.length +
                      " | Tweetable! Adding to tweet thread");                           //log parse length, success
          console.log("Tweet Added: " + parsed);
        }                                                                                //end parsing loop
        console.log("Parsing Complete");                                                 //log parsing complete
      } else {                                                                           //if thread[i] is tweet length...
        console.log("Tweetable! Adding to tweet thread");                                //log  length
        tweets.push(thread[i])                                                           //add thread[i] to tweets
        console.log("Tweet Added: " + thread[i]);
        console.log("Tweet Thread length: " + tweets.length);
      }
    }                                                                                    //end loop
  } catch (e) {                                                                          //Catch thrown error
    console.log("Parsing Error. Error: " + e);                                           //Log error
  }
//////////////////////////Split Images/////////////////////////////////////////////////////
  if (img){                                                                              //if image string has been passed...
    var imgs = img.split(",");                                                           //split CSV into individual URLs
    console.log(img + " contains " + imgs.length + " values!");                          //log number of images found
  } else {                                                                               //if no image string has been passed...
    console.log("No images passed through threading function");                          //log no images
  }                                                                                      //end image processing
//////////////////////////Output///////////////////////////////////////////////////////////
  if (r) {
    var replyTo = r
    } else {
      var replyTo = 0;                                                                       //set reply (each tweet will reply to previous, first will be null
    }
  for (i in tweets){                                                                     //for each tweet in thread...
    console.log("Tweet Attempt: " + i);                                                  //log attempt number (starting @ 0)
    try{
      if (imgs[i]) {                                                                     //if valid image URL exists...
        url = imgs[i].toString();                                                        //set URL variable for tweet function
        console.log("imgs[" + i + "]: " + imgs[i]);                                      //log image
      } else {
        url = null;
        console.log("imgs[" + i + "]: " + imgs[i]);
      }
    } catch (e) {
      url = null;                                                                        //null variable for tweet function
      console.log("imgs[" + i + "] parse error: " + e);                                  //log image error
    }
    var newTweet = sendTweet(tweets[i], replyTo, url);                                   //set reply value for next tweet as return of tweet function
    Utilities.sleep(250);                                                                //wait 1/4 second (for return value, to avoid errors)
    if (i == 0) {                                                                        //if first tweet in thread...
      var begins = newTweet                                                              //set value for first tweet ID
      console.log("Thread begins with tweet(ID): " + begins);                            //log first tweet ID
    }
    replyTo = newTweet                                                                   //set replyTo value to response of last tweet
    if (replyTo == undefined) {                                                          //if no response...
      console.log("replyTo undefined! Breaking loop...");                                //log undefined response
      break;                                                                             //break thread, do not tweet more
    } else {                                                                             //if response...
      console.log("Next Reply To: " + replyTo);                                          //log reply
    }
  }                                                                                      //end thread tweeting
  return begins;
}                                                                                        //END