title: What's the meaning of 'inoremap' in vimrc
body: <p>There is a line below in <code>vimrc</code> example file</p>
  
  <pre><code>inoremap Ctrl-u Ctrl-G u Ctrl-u
  </code></pre>
  
  <p>What's the meaning of <code>inoremap</code> and what's the function of this line?</p>