function buildContentRange (rangeStart, rangeEnd, fullLength) {
  // 1. Let contentRange be `bytes `.
  let contentRange = 'bytes '

  // 2. Append rangeStart, serialized and isomorphic encoded, to contentRange.
  contentRange += isomorphicEncode(`${rangeStart}`)

  // 3. Append 0x2D (-) to contentRange.
  contentRange += '-'

  // 4. Append rangeEnd, serialized and isomorphic encoded to contentRange.
  contentRange += isomorphicEncode(`${rangeEnd}`)

  // 5. Append 0x2F (/) to contentRange.
  contentRange += '/'

  // 6. Append fullLength, serialized and isomorphic encoded to contentRange.
  contentRange += isomorphicEncode(`${fullLength}`)

  // 7. Return contentRange.
  return contentRange
}
@see https://fetch.spec.whatwg.org/#build-a-content-range
@param {number} rangeStart
@param {number} rangeEnd
@param {number} fullLength