title: os.path.getsize returns 0 although folder has files in it (Python 3.5)
body: <p>I am trying to create a program which auto-backups some folders under certain circumstances. 
  I try to compare the size of two folders (source and dest), source has files in it, a flac file and a subfolder with a text file whereas dest is empty.</p>
  
  <p>This is the code I've written so far:</p>
  
  <pre><code>import os.path
  sls = os.path.getsize('D:/autobu/source/')
  dls = os.path.getsize('D:/autobu/dest/')
  print(sls)
  print(dls)
  if sls &gt; dls:
      print('success')
  else:
      print('fail')
  </code></pre>
  
  <p>And the output is this:</p>
  
  <pre><code>0
  0
  fail
  </code></pre>
  
  <p>What have I done wrong? Have I misunderstood how getsize functions?</p>