title: About sequences & identifier
body: <p>I want to change <strong>Invoice format</strong> in which 2015/06/0001 , where year is <strong>current year</strong>, Month is set to <strong>next month of worked out month</strong>  &amp; Last is unique count for that month.
    I have tried with sequences but month can not set to next of worked out.
  I have set prefix </p>
  
  <blockquote>
    <p>ABC/%(year)s/%(month)s/</p>
  </blockquote>
  
  <p>but I want month as a next month of worked out.</p>