Imports github.com/juju/errors github.com/juju/juju/mongo github.com/juju/loggo github.com/juju/txn github.com/juju/utils/set gopkg.in/juju/blobstore.v2 gopkg.in/mgo.v2 gopkg.in/mgo.v2/bson gopkg.in/mgo.v2/txn Standard library imports fmt io