title: create and initialize python list
body: <p>I am stuck on making list using python.</p>
  
  <p>I want to make m x n files such as file00.txt, file01.txt, ..., and file99.txt, but when I tried to make it, it shows some errors. Please let me help out.</p>
  
  <pre><code>filename = []
  
  for i in range(0, sm):
      filename.append('') 
      for j in range(0, sn):
          filename[i].append('')
  </code></pre>
  
  <p>Thanks.</p>