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

export const fromAlter = (n) => isNum(n) ? major(n) : null

var objHeight = function objHeight(p) {
  if (!p) return -Infinity;
  var f = p[1] * 7;
  var o = tonalPitches.isNum(p[2]) ? p[2] : -Math.floor(f / 12) - 10;
  return f + o * 12;
};

const objHeight = function (p) {
  if (!p) return -Infinity
  const f = p[1] * 7
  const o = isNum(p[2]) ? p[2] : -Math.floor(f / 12) - 10
  return f + o * 12
}

var fromAlter = function fromAlter(n) {
  return tonalPitches.isNum(n) ? major(n) : null;
};

const objHeight = function (p) {
  if (!p) return -Infinity
  const f = p[1] * 7
  const o = tonalPitches.isNum(p[2]) ? p[2] : -Math.floor(f / 12) - 10
  return f + o * 12
}