code: func (c *Client) UpdateRegistration(reg contract.Registration) error {
  	conn := c.Pool.Get()
  	defer conn.Close()
  
  	err := deleteRegistration(conn, reg.ID)
  	if err != nil {
  		return err
  	}
  
  	_, err = addRegistration(conn, reg)
  	return err
  }
docs: // Update a registration
  // UnexpectedError - problem updating in database
  // NotFound - no registration with the ID was found