static toHex(data) {
    const arr = shaka.util.BufferUtils.toUint8(data);
    let hex = '';
    for (let value of arr) {
      value = value.toString(16);
      if (value.length == 1) {
        value = '0' + value;
      }
      hex += value;
    }
    return hex;
  }
Convert a buffer to a hex string.
@param {BufferSource} data
@return {string}
@export