code: func NewCustomDatastoreFlag(ctx context.Context) (*DatastoreFlag, context.Context) {
  	v := &DatastoreFlag{}
  	v.DatacenterFlag, ctx = NewDatacenterFlag(ctx)
  	return v, ctx
  }
docs: // NewCustomDatastoreFlag creates and returns a new DatastoreFlag without
  // trying to retrieve an existing one from the specified context.