class Lato::Invitation

def send_invite
  if accepted?
    errors.add(:base, :already_accepted)
    return false
  end
  if c_email_invite_semaphore
    errors.add(:base, :email_sending_limit)
    return false
  end
  delivery = Lato::InvitationMailer.invite_mail(id).deliver_now
  unless delivery
    errors.add(:base, :email_sending_error)
    return false
  end
  c_email_invite_semaphore(true)
  true
end