Godeps/_workspace/src/gopkg.in/mgo.v2/session.go
func (c *Collection) With(s *Session) *Collection {
	newdb := *c.Database
	newdb.Session = s
	newc := *c
	newc.Database = &newdb
	return &newc
}
func (c *Collection) With(s *Session) *Collection {
	newdb := *c.Database
	newdb.Session = s
	newc := *c
	newc.Database = &newdb
	return &newc
}
// With returns a copy of c that uses session s.