span> : <code class="type">bounds:int list -> int <a href="OpamHeuristic.html#TYPEstate">state</a> -> int <a href="OpamHeuristic.html#TYPEstate">state</a> option</code></pre><div class="info">
Given a list of bounds and a tuple, return the next tuple which
    satisfies the bounds (each component will be stricly lesser than
    the bounds). The enumeration respect the following invariant:
<p>
<ul>
<li>it is complete, eg. all the state are enumerated until <code class="code">None</code> is
      returned.</l