title: Delete selected keys from Dart Map
body: <p>What is the Dart idiomatic way to remove selected keys from a Map?
  Below I'm using a temporary emptyList to hold String keys.
  Is there a cleaner way?</p>
  
  <pre class="lang-dart prettyprint-override"><code>List&lt;String&gt; emptyList = new List&lt;String&gt;();
  _objTable.keys.forEach((String name) { 
    if (_objTable[name].indices.isEmpty) {
      emptyList.add(name);
      print("OBJ: deleting empty object=$name loaded from url=$url");
    } 
  });
  emptyList.forEach((String name) =&gt; _objTable.remove(name));
  </code></pre>