code: function createIcon (buf, maxAge) {
    return {
      body: buf,
      headers: {
        'Cache-Control': 'public, max-age=' + Math.floor(maxAge / 1000),
        'ETag': etag(buf)
      }
    }
  }
docs: Create icon data from Buffer and max-age.
  
  @private
  @param {Buffer} buf
  @param {number} maxAge
  @return {object}