index.js
function add (a, b) {
  var fifths = a[0] + b[0]
  var octaves = a[1] === null || b[1] === null ? null : a[1] + b[1]
  return [fifths, octaves]
}
function add (a, b) {
  var fifths = a[0] + b[0]
  var octaves = a[1] === null || b[1] === null ? null : a[1] + b[1]
  return [fifths, octaves]
}
function add ( a , b ) { var fifths = a [ 0 ] + b [ 0 ] var octaves = a [ 1 ] === null || b [ 1 ] === null ? null : a [ 1 ] + b [ 1 ] return [ fifths , octaves ] }
Add two pitches. Can be used to tranpose pitches.

@param {Array} first - first pitch
@param {Array} second - second pitch
@return {Array} both pitches added

@example
operator.add([3, 0, 0], [4, 0, 0]) // => [0, 0, 1]
Add two pitches . Can be used to tranpose pitches .