title: can os.path.join (or other python method) append a '/' automatically for the case of the directory?
body: <p>The <code>os.path.join(a, b)</code> method will generate a string ending without '/' no matter it is a file or directory. Now, is there any way (or any other <code>os.path</code> method) to get a '/' automatically for the case of the directory?</p>