code: func (c *ExampleService) CreateUser(ctx context.Context, u *platform.User) error {
  	err := c.kv.Update(func(tx Tx) error {
  		unique := c.uniqueExampleName(ctx, tx, u)
  
  		if !unique {
  			// TODO: make standard error
  			return &platform.Error{
  				Code: platform.EConflict,
  				Msg:  fmt.Sprintf("user with name %s already exists", u.Name),
  			}
  		}
  
  		u.ID = c.idGenerator.ID()
  
  		return c.putUser(ctx, tx, u)
  	})
  
  	if err != nil {
  		return &platform.Error{
  			Err: err,
  			Op:  "kv/" + platform.OpCreateUser,
  		}
  	}
  
  	return nil
  }
docs: // CreateUser creates a platform example and sets b.ID.