Godeps/_workspace/src/gopkg.in/mgo.v2/session.go
func (s *Session) Run(cmd interface{}, result interface{}) error {
	return s.DB("admin").Run(cmd, result)
}
func (s *Session) Run(cmd interface{}, result interface{}) error {
	return s.DB("admin").Run(cmd, result)
}
// Run issues the provided command on the "admin" database and
// and unmarshals its result in the respective argument. The cmd
// argument may be either a string with the command name itself, in
// which case an empty document of the form bson.M{cmd: 1} will be used,
// or it may be a full command document.
//
// Note that MongoDB considers the first marshalled key as the command
// name, so when providing a command with options, it's important to
// use an ordering-preserving document, such as a struct value or an
// instance of bson.D.  For instance:
//
//     db.Run(bson.D{{"create", "mycollection"}, {"size", 1024}})
//
// For commands on arbitrary databases, see the Run method in
// the Database type.
//
// Relevant documentation:
//
//     http://www.mongodb.org/display/DOCS/Commands
//     http://www.mongodb.org/display/DOCS/List+of+Database+CommandSkips
//