why vim expand doesn't work
<p>I type <code>:echo expand("&lt;cword&gt;")</code>, vim shall show the word on the cursor.
But when I type <code>:tag expand("&lt;cword&gt;")</code>, it prompts:</p>

<blockquote>
  <p>E426: tag not found: expand(</p>
</blockquote>

<p>It seems that, the expand function is not called on the tag function, <code>expand(</code> is sent to <code>tag</code> as a parameter.</p>

<p>Thanks in advance for any insights.
Any reference is prefered.</p>