code: func (c *Client) AddRegistration(reg contract.Registration) (id string, err error) {
  	conn := c.Pool.Get()
  	defer conn.Close()
  
  	if reg.ID != "" {
  		_, err = uuid.Parse(reg.ID)
  		if err != nil {
  			return "", db.ErrInvalidObjectId
  		}
  	}
  
  	return addRegistration(conn, reg)
  }
docs: // Add a new registration
  // UnexpectedError - failed to add to database