code: func (o *InvitationManager) FilterByUser(username string, status string) ([]JoinOrganizationInvitation, error) {
  	orgRequests := []JoinOrganizationInvitation{}
  	if status == "" {
  		return o.GetByUser(username)
  	}
  	qry := bson.M{
  		"user":   username,
  		"status": status,
  	}
  	err := o.collection.Find(qry).All(&orgRequests)
  	return orgRequests, err
  }
docs: // FilterByUser gets all invitations for a user, filtered on status