remove unused imports, minor formatting cleanup

tools/autojump_ipython.py

@@ -4,27 +4,31 @@ IPython autojump magic
 Written by keith hughitt <keith.hughitt@gmail.com>, based on an earlier
 version by Mario Pastorelli <pastorelli.mario@gmail.com>.
 
-To install, `create a new IPython user profile <http://ipython.org/ipython-doc/stable/config/ipython.html#configuring-ipython>`_
-if you have not already done so by running:
+To install, create a new IPython user profile by running:
 
     ipython profile create
 
-And copy this file into the "startup" folder of your new profile (e.g. 
+And copy this file into the "startup" folder of your new profile (e.g.
 "$HOME/.config/ipython/profile_default/startup/").
 
 @TODO: extend %cd to call "autojump -a"
 """
-import os
-import subprocess as sub
-from IPython.core.magic import (register_line_magic, register_cell_magic,
-                                register_line_cell_magic)
+from subprocess import Popen
+from subprocess import PIPE
+
+from IPython.core.magic import register_line_magic
 
 ip = get_ipython()
 
+
 @register_line_magic
 def j(path):
     cmd = ['autojump'] + path.split()
-    newpath = sub.Popen(cmd, stdout=sub.PIPE, shell=False).communicate()[0].strip()
+    newpath = Popen(
+            cmd,
+            stdout=PIPE,
+            shell=False).communicate()[0].strip()
+
     if newpath:
         ip.magic('cd %s' % newpath.decode('utf-8'))