How to use the tonal-pitches.ivlPitch function in tonal-pitches

function trBy (i, p) {
  if (p === null) return null
  const f = i[1] + p[1]
  if (p.length === 2) return pcPitch(f)
  const o = i[2] + p[2]
  if (p.length === 3) return notePitch(f, o)
  return ivlPitch(f, o)
}

  return (n) => tr(t, ivlPitch(n, 0))
}

function trBy(i, p) {
  if (p === null) return null;
  var f = i[1] + p[1];
  if (p.length === 2) return tonalPitches.pcPitch(f);
  var o = i[2] + p[2];
  if (p.length === 3) return tonalPitches.notePitch(f, o);
  return tonalPitches.ivlPitch(f, o);
}

function substr (a, b) {
  if (a.length !== b.length) return null
  return isPitchClass(a)
    ? ivlPitch(b[1] - a[1])
    : ivlPitch(b[1] - a[1], b[2] - a[2])
}

var relative = function relative(rel, key) {
  var r = asKey(rel);
  if (hasTonic(r)) return null;
  var k = asKey(key);
  if (!hasTonic(k)) return null;
  var i = tonalPitches.ivlPitch(modeNum(r) - modeNum(k), 0);
  var tonic = tonalDistances.transpose(k.tonic, i);
  return build(tonic, rel);
};

function substr (a, b) {
  if (a.length !== b.length) return null
  return isPitchClass(a)
    ? ivlPitch(b[1] - a[1])
    : ivlPitch(b[1] - a[1], b[2] - a[2])
}