code: func (q *Query) Batch(n int) *Query {
  	if n == 1 {
  		// Server interprets 1 as -1 and closes the cursor (!?)
  		n = 2
  	}
  	q.m.Lock()
  	q.op.limit = int32(n)
  	q.m.Unlock()
  	return q
  }
docs: // Batch sets the batch size used when fetching documents from the database.
  // It's possible to change this setting on a per-session basis as well, using
  // the Batch method of Session.
  //
  // The default batch size is defined by the database itself.  As of this
  // writing, MongoDB will use an initial size of min(100 docs, 4MB) on the
  // first batch, and 4MB on remaining ones.