title: What is better to use: Dictionary<>.ForEach(pair =>) or Dictionary<>.Keys.ForEach(key =>)?
body: <p>If I have access only keys from a <code>Dictionary&lt;TKey, TValue&gt;</code> what is better to use:</p>
  
  <pre><code>Dictionary&lt;TKey, TValue&gt;.ForEach(pair =&gt; action(pair.Key))
  </code></pre>
  
  <p>or</p>
  
  <pre><code>Dictionary&lt;TKey, TValue&gt;.Keys.ForEach(key =&gt; action(key))
  </code></pre>
  
  <p>Which method is more 'best-practice' ? Speed in both cases I think seems to be very similar.</p>