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
}
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
}
// 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.