lass="comment">// <a class="link" href="basic_environment.html#idp51485504-bb">public member functions</a></span>
  <span class="identifier">iterator</span> <a class="link" href="basic_environment.html#idp51486000-bb"><span class="identifier">begin</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  <span class="identifier">const_iterator</span> <a class="link" href="basic_environment.html#idp51487008-bb"><span class="identifier">begin</span></a><span class