title: No such file or directory when starting directory name with /
body: <p>I am just confusing that when I apply:</p>
  
  <pre><code>os.listdir("HW-3/data_sets/")
  </code></pre>
  
  <p>It works well! and list all the name of files under that directories.However, when I added an additional slash. In my mind, it should be fine. </p>
  
  <pre><code>os.listdir("/HW-3/data_sets/")
  </code></pre>
  
  <p>But it shows error message:</p>
  
  <pre><code>OSError: [Errno 2] No such file or directory: '/HW-3/data_sets'
  </code></pre>
  
  <p>It let me think about this program is so unstable. How can I let it work well even when user input <code>'/HW-3/data_sets'</code>? Thanks in advance!</p>