code: func InitModels() {
  	index := mgo.Index{
  		Key:    []string{"sessionkey"},
  		Unique: true,
  	}
  
  	db.EnsureIndex(mongoRegistrationsInProgressCollectionName, index)
  
  	index = mgo.Index{
  		Key:    []string{"emailvalidationkey"},
  		Unique: false, // Uniqueness is enforced in the respective ongoing validation collection
  	}
  
  	db.EnsureIndex(mongoRegistrationsInProgressCollectionName, index)
  
  	index = mgo.Index{
  		Key:    []string{"phonevalidationkey"},
  		Unique: false, // Uniqueness is enforced in the respective ongoing validation collection
  	}
  
  	db.EnsureIndex(mongoRegistrationsInProgressCollectionName, index)
  
  	automaticExpiration := mgo.Index{
  		Key:         []string{"createdat"},
  		ExpireAfter: time.Second * 60 * 60 * 24, // Remove after one day
  		Background:  true,
  	}
  
  	db.EnsureIndex(mongoRegistrationsInProgressCollectionName, automaticExpiration)
  }
docs: // InitModels intializes the mongo models