diff --git a/scratch/walking.py b/scratch/walking.py
new file mode 100755
index 0000000..c6143c7
--- /dev/null
+++ b/scratch/walking.py
@@ -0,0 +1,104 @@
+#!/usr/bin/env python3
+
+import os
+import shutil
+import tempfile
+
+from swh.core import hashutil
+
+
+def compute_hashes(dirpath, filename):
+    """Given a fullname, compute its hashes.
+
+    Args:
+        dirpath: the absolute path of the filename
+        filename: the file's name
+
+    Returns:
+        The computed hash for that filename.
+
+    Assumes:
+        The full computed path exists.
+
+    """
+    fullname = os.path.join(dirpath, filename)
+    return hashutil.hashfile(fullname)
+
+
+# echo <git ls-tree format input> | git mktree --missing
+
+def compute_directory_hash(dirpath, hashes):
+    """Compute a directory git sha1 for a dirpath.
+
+    Args:
+        dirpath: the absolute path of the directory
+        hashes: list of dictionaries with keys:
+            - sha1_git:
+            - path: directory parent of the filename
+            - name: file's name
+
+        Returns:
+            sha1 git of the directory
+
+        Assumes:
+            Every path exists.
+    """
+    def row_entry_tree_format(hashes):
+        return map(lambda entry:
+                   entry['perms'] + b' ' + entry['name'] + b'\0' +
+                   entry['sha1_git'],
+                   hashes)
+
+    rows = list(row_entry_tree_format(hashes))
+    return hashutil.hashdata(b''.join(rows),
+                             algorithms=['sha1_tree_git'])
+
+
+def walk_from(dir):
+    for dirpath, dirnames, filenames in os.walk(dir, topdown=False):
+        print('dirpath: %s\ndirnames: %s' % (dirpath, dirnames))
+        dir_hashes = []
+        for filename in filenames:
+            fullname = os.path.join(dirpath, filename)
+            print('filename: %s' % filename)
+            hashes = compute_hashes(dirpath, fullname)
+            hashes.update({
+                'name': bytes(filename, 'utf-8'),
+                'parent': dirpath,
+                'perms': bytes('100644', 'utf-8'),
+            })
+            print('hashes: %s' % hashes)
+            dir_hashes.append(hashes)
+
+        tree_hash = compute_directory_hash(dirpath, dir_hashes)
+        tree_hash.update({
+            'name': dirpath,
+            'type': 'tree'
+        })
+        print("directory sha1: %s" % tree_hash)
+        print()
+
+
+def write_file(file, content):
+    with open(file, 'w') as f:
+        f.write(content)
+
+# prepare some arborescence with dirs and files to walk it
+scratch_folder_root = tempfile.mktemp(prefix='swh.loader.dir', suffix='.tmp', dir='/tmp')
+scratch_folder_foo = os.path.join(scratch_folder_root, 'foo')
+os.makedirs(scratch_folder_foo, exist_ok=True)
+scratch_folder_bar = os.path.join(scratch_folder_root, 'bar/barfoo')
+os.makedirs(scratch_folder_bar, exist_ok=True)
+
+scratch_file = os.path.join(scratch_folder_foo, 'quotes.md')
+write_file(scratch_file,
+           'Shoot for the moon. Even if you miss, you\'ll land among the stars.')
+
+scratch_file2 = os.path.join(scratch_folder_bar, 'another-quote.org')
+write_file(scratch_file2,
+           'A Victory without danger is a triumph without glory.\n-- Pierre Corneille')
+
+walk_from(scratch_folder_root)
+
+# clean up
+shutil.rmtree(scratch_folder_root, ignore_errors = True)