title: vim mapping key to the command that require argument
body: <p>As the title, let say I have to run this command in vim <code>&lt;command&gt; &lt;argument&gt;</code>.</p>
  
  <p>In my <code>.vimrc</code> I set <code>let mapleader = ,</code></p>
  
  <p>So in normal mode, if I type <code>,ab</code> then vim will run command <code>&lt;command&gt; ab</code>. if I type <code>,xyz</code> then vim will run command <code>&lt;command&gt; xyz</code>.</p>
  
  <p>How to do that?</p>