def bandit_session_convert!(exp, alt=nil, count=1)
      cookiename = "bandit_#{exp}".intern
      cookiename_converted = "bandit_#{exp}_converted".intern
      alt ||= cookies.signed[cookiename]
      unless alt.nil? or cookies.signed[cookiename_converted]
        Bandit.get_experiment(exp).convert!(alt, count)
        cookies.delete(cookiename)
      end
    end
def bandit_session_convert!(exp, alt=nil, count=1)
      cookiename = "bandit_#{exp}".intern
      cookiename_converted = "bandit_#{exp}_converted".intern
      alt ||= cookies.signed[cookiename]
      unless alt.nil? or cookies.signed[cookiename_converted]
        Bandit.get_experiment(exp).convert!(alt, count)
        cookies.delete(cookiename)
      end
    end
expects a session cookie, deletes it, will convert again