--- a/decoupage/index.py	Fri Mar 31 16:38:02 2017 -0700
+++ b/decoupage/index.py	Fri Mar 31 17:06:59 2017 -0700
@@ -7,19 +7,25 @@
 
 import argparse
 import os
-import subprocess
 import sys
 
 here = os.path.dirname(os.path.realpath(__file__))
-string = (str, unicode)
 
 def index(directory):
+    """
+    returns string representation of directory
+    """
+
     return '\n'.join(['{name} = {name}'.format(name=name)
-                      for name in sorted(os.listdir(directory), key=lambda name: name.lower())
+                      for name in sorted(os.listdir(directory),
+                                         key=lambda name: name.lower())
                       if not name.startswith('.')])
 
+
 def main(args=sys.argv[1:]):
+    """CLI"""
 
+    # parse command line
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument('directory', help='directory')
     parser.add_argument('-o', '--output', dest='output',
@@ -27,5 +33,13 @@
                         help='output')
     options = parser.parse_args(args)
 
+    # sanity
+    if not os.path.isdir(options.directory):
+        parser.error("Not a directory: '{}'".format(options.directory))
+
+    # output
+    options.output.write(index(options.directory))
+
+
 if __name__ == '__main__':
     main()