docs: function defaults(opts) {
    opts = opts || {}
  
    if (!opts.streamer) {
      throw new Error('No streamer found. Must pass a streamer to multipart-pipe')
    }
  
    opts.limit = opts.limit === undefined ? '128mb' : opts.limit;
    opts.limit = typeof opts.limit === 'string' ? parseBytes(opts.limit) : opts.limit;
    opts.allow = opts.allow instanceof RegExp ? opts.allow : new RegExp(opts.allow || '.*');
  
    if (!opts.filename || typeof opts.filename !== 'function') {
      opts.filename = function (filename, mime) { return filename; };
    }
  
    return opts
  }