git rebase -i $(git rev-list --max-parents=0 HEAD) HEAD

// The keys and notes variables store the piano keys
const keys = ['c-key', 'd-key', 'e-key', 'f-key', 'g-key', 'a-key', 'b-key', 'high-c-key', 'c-sharp-key', 'd-sharp-key', 'f-sharp-key', 'g-sharp-key', 'a-sharp-key'];
/* */
const notes = [];
keys.forEach(function(key){
  notes.push(document.getElementById(key));
})
// Write named functions that change the color of the keys below
const keyPlay = (event) => {
  event.target.style.backgroundColor = 'blue';
};
const keyReturn = (event) => {
  event.target.style.backgroundColor = '';
};
// Write a named function with event handler properties
const eventAssignment = (note) => {
  note.onmousedown = () => {
    keyPlay(event);
  }
  note.onmouseup = () => {
    keyReturn(event);
  }
};
// Write a loop that runs the array elements through the function
notes.forEach(eventAssignment);
// These variables store the buttons that progress the user through the lyrics
let nextOne = document.getElementById('first-next-line');
let nextTwo = document.getElementById('second-next-line');
let nextThree = document.getElementById('third-next-line');
let startOver = document.getElementById('fourth-next-line');
// This variable stores the '-END' lyric element
let lastLyric = document.getElementById('column-optional');
// These statements are "hiding" all the progress buttons, but the first one
nextTwo.hidden = true;
nextThree.hidden = true;
startOver.hidden= true;
// Write anonymous event handler property and function for the first progress button
nextOne.onclick = () => {
  nextTwo.hidden = false;
  nextOne.hidden = true;
  /* */
  document.getElementById('letter-note-five').innerHTML = 'D';
  document.getElementById('letter-note-six').innerHTML = 'C';
};
// Write anonymous event handler property and function for the second progress button
nextTwo.onclick = () => {
  nextThree.hidden = false;
  nextTwo.hidden = true;
  /* */
  document.getElementById('word-five').innerHTML = 'DEAR';
  document.getElementById('word-six').innerHTML = 'FRI-';
  /* */
  lastLyric.style.display = 'inline-block';
  /* */
  document.getElementById('letter-note-three').innerHTML = 'G';
  document.getElementById('letter-note-four').innerHTML = 'E';
  document.getElementById('letter-note-five').innerHTML = 'C';
  document.getElementById('letter-note-six').innerHTML = 'B';
};
// Write anonymous event handler property and function for the third progress button
nextThree.onclick = () => {
  startOver.hidden = false;
  nextThree.hidden = true;
  /* */
  document.getElementById('word-one').innerHTML = 'HAP-';
  document.getElementById('word-two').innerHTML = 'PY';
  document.getElementById('word-three').innerHTML = 'BIRTH';
  document.getElementById('word-four').innerHTML = 'DAY';
  document.getElementById('word-five').innerHTML = 'TO';
  document.getElementById('word-six').innerHTML = 'YOU!';
  /* */
  document.getElementById('letter-note-one').innerHTML = 'F';
  document.getElementById('letter-note-two').innerHTML = 'F';
  document.getElementById('letter-note-three').innerHTML = 'E';
  document.getElementById('letter-note-four').innerHTML = 'C';
  document.getElementById('letter-note-five').innerHTML = 'D';
  document.getElementById('letter-note-six').innerHTML = 'C';
  /* */
  lastLyric.style.display = 'none';
};

// This is the event handler property and function for the startOver button
startOver.onclick = function() {
  nextOne.hidden = false;
  startOver.hidden = true;
   document.getElementById('word-one').innerHTML = 'HAP-';
  document.getElementById('letter-note-one').innerHTML = 'G';
  document.getElementById('word-two').innerHTML = 'PY';
  document.getElementById('letter-note-two').innerHTML = 'G';
  document.getElementById('word-three').innerHTML = 'BIRTH-';
  document.getElementById('letter-note-three').innerHTML = 'A';
  document.getElementById('word-four').innerHTML = 'DAY';
  document.getElementById('letter-note-four').innerHTML = 'G';
  document.getElementById('word-five').innerHTML = 'TO';
  document.getElementById('letter-note-five').innerHTML = 'C';
  document.getElementById('word-six').innerHTML = 'YOU!';
  document.getElementById('letter-note-six').innerHTML = 'B';
};