diff --git a/scratch/walking.py b/scratch/walking.py
index e8f36a2..b485168 100755
--- a/scratch/walking.py
+++ b/scratch/walking.py
@@ -1,91 +1,99 @@
 #!/usr/bin/env python3
 
+# Tryouts scratch buffer
+# Not for production
+
+# Copyright (C) 2015  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
 import os
 import shutil
 import tempfile
 
 from swh.loader.dir.git import git, utils
 
 
 def write_file(root, file, content):
     """Write some content in a file.
 
     """
     filename = os.path.join(root, file)
     with open(filename, 'w') as f:
         f.write(content)
 
 
 def mkdir(root, name):
     """Create a directory path on disk.
 
     """
     full_foldername = os.path.join(root, name)
     os.makedirs(full_foldername, exist_ok=True)
     return full_foldername
 
 
 def git_ls_tree_rec(hashes, info):
     """Display the computed result for debug purposes.
 
     """
     for entry in hashes.keys():
         entry_properties = hashes[entry]
         print("entry name: %s" % entry)
         for file in entry_properties:
             sha1 = utils.hash_to_hex(file['sha1_git'])
             print("%s %s %s\t%s" % (file['perms'].value.decode('utf-8'),
                                     file['type'].value.decode('utf-8'),
                                     sha1,
                                     file['name'].decode('utf-8')))
         print()
 
     revision = git.compute_revision_git_sha1(hashes, info)
     print('revision %s -> directory %s' % (
         utils.hash_to_hex(revision['sha1_git']),
         utils.hash_to_hex(hashes['<root>'][0]['sha1_git'])
     ))
 
 
 ### setup - prepare some arborescence with dirs and files to walk it
 
 tempfilename = tempfile.mktemp(prefix='swh.loader.dir', suffix='.tmp',
                                dir='/tmp')
 # want the same name for idempotency
 scratch_folder_root = mkdir(tempfilename, 'tmp')
 
 mkdir(scratch_folder_root, 'empty-folder')
 scratch_folder_foo = mkdir(scratch_folder_root, 'foo')
 scratch_folder_bar = mkdir(scratch_folder_root, 'bar/barfoo')
 
 write_file(scratch_folder_foo,
            'quotes.md',
            'Shoot for the moon. Even if you miss, you\'ll land among '
            'the stars.')
 
 write_file(scratch_folder_bar,
            'another-quote.org',
            'A Victory without danger is a triumph without glory.\n'
            '-- Pierre Corneille')
 
 ADDITIONAL_INFO = {
     'revision_author_name': 'swh author',
     'revision_author_email': 'swh@inria.fr',
     'revision_author_date': '1444054085',
     'revision_author_offset': '+0200',
     'revision_committer_name': 'swh committer',
     'revision_committer_email': 'swh@inria.fr',
     'revision_committer_date': '1444054085',
     'revision_committer_offset': '+0200',
     'revision_type': 'dir',
     'revision_message': 'synthetic revision message'
 }
 
 # when
 hashes = git.walk_and_compute_sha1_from_directory(scratch_folder_root)
 
 # then
 git_ls_tree_rec(hashes, ADDITIONAL_INFO)
 
 ### teardown
 shutil.rmtree(tempfilename, ignore_errors = True)