index.js
function parseDecorator (fn) {
  return function (pitch) {
    var p = asArray(pitch)
    return p ? fn(p) : null
  }
}
function parseDecorator (fn) {
  return function (pitch) {
    var p = asArray(pitch)
    return p ? fn(p) : null
  }
}
function parseDecorator ( fn ) { return function ( pitch ) { var p = asArray ( pitch ) return p ? fn ( p ) : null } }
decorate a function to force the param to be an array-pitch
decorate a function to force the param to be an array - pitch