diff --git a/tools/git_sync_cl_chain.py b/tools/git_sync_cl_chain.py
index 0fd65c6..f89bde6 100755
--- a/tools/git_sync_cl_chain.py
+++ b/tools/git_sync_cl_chain.py
@@ -32,165 +32,189 @@
 
 REPO_ROOT = defines.REPO_ROOT
 
+
 class Repo(object):
-  def __init__(self, name, is_current, upstream):
-    self.name = name
-    self.is_current = is_current
-    self.upstream = upstream
+
+    def __init__(self, name, is_current, upstream):
+        self.name = name
+        self.is_current = is_current
+        self.upstream = upstream
+
 
 def ParseOptions(argv):
-  result = optparse.OptionParser()
-  result.add_option('--bypass-hooks',
-                    help='Bypass presubmit hooks',
-                    action='store_true')
-  result.add_option('--delete', '-d',
-                    help='Delete closed branches',
-                    choices=['y', 'n', 'ask'],
-                    default='ask')
-  result.add_option('--from_branch', '-f',
-                    help='Uppermost upstream to sync from',
-                    default='main')
-  result.add_option('--leave_upstream', '--leave-upstream',
-                    help='To not update the upstream of the first open branch',
-                    action='store_true')
-  result.add_option('--message', '-m',
-                    help='Message for patchset', default='Sync')
-  result.add_option('--rebase',
-                    help='To use `git pull --rebase` instead of `git pull`',
-                    action='store_true')
-  result.add_option('--no_upload', '--no-upload',
-                    help='Disable uploading to Gerrit', action='store_true')
-  result.add_option('--skip_main', '--skip-main',
-                    help='Disable syncing for main',
-                    action='store_true')
-  (options, args) = result.parse_args(argv)
-  options.upload = not options.no_upload
-  assert options.delete != 'y' or not options.leave_upstream, (
-      'Inconsistent options: cannot leave the upstream of the first open ' +
-      'branch (--leave_upstream) and delete the closed branches at the same ' +
-      'time (--delete).')
-  assert options.message, 'A message for the patchset is required.'
-  assert len(args) == 0
-  return options
+    result = optparse.OptionParser()
+    result.add_option('--bypass-hooks',
+                      help='Bypass presubmit hooks',
+                      action='store_true')
+    result.add_option('--delete',
+                      '-d',
+                      help='Delete closed branches',
+                      choices=['y', 'n', 'ask'],
+                      default='ask')
+    result.add_option('--from_branch',
+                      '-f',
+                      help='Uppermost upstream to sync from',
+                      default='main')
+    result.add_option(
+        '--leave_upstream',
+        '--leave-upstream',
+        help='To not update the upstream of the first open branch',
+        action='store_true')
+    result.add_option('--message',
+                      '-m',
+                      help='Message for patchset',
+                      default='Sync')
+    result.add_option('--rebase',
+                      help='To use `git pull --rebase` instead of `git pull`',
+                      action='store_true')
+    result.add_option('--no_upload',
+                      '--no-upload',
+                      help='Disable uploading to Gerrit',
+                      action='store_true')
+    result.add_option('--skip_main',
+                      '--skip-main',
+                      help='Disable syncing for main',
+                      action='store_true')
+    (options, args) = result.parse_args(argv)
+    options.upload = not options.no_upload
+    assert options.delete != 'y' or not options.leave_upstream, (
+        'Inconsistent options: cannot leave the upstream of the first open ' +
+        'branch (--leave_upstream) and delete the closed branches at the same '
+        + 'time (--delete).')
+    assert options.message, 'A message for the patchset is required.'
+    assert len(args) == 0
+    return options
+
 
 def main(argv):
-  options = ParseOptions(argv)
-  with utils.ChangedWorkingDirectory(REPO_ROOT, quiet=True):
-    branches = [
-        parse(line)
-        for line in utils.RunCmd(['git', 'branch', '-vv'], quiet=True)]
+    options = ParseOptions(argv)
+    with utils.ChangedWorkingDirectory(REPO_ROOT, quiet=True):
+        branches = [
+            parse(line)
+            for line in utils.RunCmd(['git', 'branch', '-vv'], quiet=True)
+        ]
 
-    current_branch = None
-    for branch in branches:
-      if branch.is_current:
-        current_branch = branch
-        break
-    assert current_branch is not None
+        current_branch = None
+        for branch in branches:
+            if branch.is_current:
+                current_branch = branch
+                break
+        assert current_branch is not None
 
-    if is_root_branch(current_branch, options):
-      print('Nothing to sync')
-      return
+        if is_root_branch(current_branch, options):
+            print('Nothing to sync')
+            return
 
-    stack = []
-    while current_branch:
-      stack.append(current_branch)
-      if is_root_branch(current_branch, options):
-        break
-      current_branch = get_branch_with_name(current_branch.upstream, branches)
+        stack = []
+        while current_branch:
+            stack.append(current_branch)
+            if is_root_branch(current_branch, options):
+                break
+            current_branch = get_branch_with_name(current_branch.upstream,
+                                                  branches)
 
-    closed_branches = []
-    has_seen_local_branch = False # A branch that is not uploaded.
-    has_seen_open_branch = False # A branch that is not closed.
-    while len(stack) > 0:
-      branch = stack.pop()
+        closed_branches = []
+        has_seen_local_branch = False  # A branch that is not uploaded.
+        has_seen_open_branch = False  # A branch that is not closed.
+        while len(stack) > 0:
+            branch = stack.pop()
 
-      utils.RunCmd(['git', 'checkout', branch.name], quiet=True)
+            utils.RunCmd(['git', 'checkout', branch.name], quiet=True)
 
-      status = get_status_for_current_branch(branch)
-      print('Syncing %s (status: %s)' % (branch.name, status))
+            status = get_status_for_current_branch(branch)
+            print('Syncing %s (status: %s)' % (branch.name, status))
 
-      pull_for_current_branch(branch, options)
+            pull_for_current_branch(branch, options)
 
-      if branch.name == 'main':
-        continue
+            if branch.name == 'main':
+                continue
 
-      if status == 'closed':
-        assert not has_seen_local_branch, (
-            'Unexpected closed branch %s after new branch' % branch.name)
-        assert not has_seen_open_branch, (
-            'Unexpected closed branch %s after open branch' % branch.name)
-        closed_branches.append(branch.name)
-        continue
+            if status == 'closed':
+                assert not has_seen_local_branch, (
+                    'Unexpected closed branch %s after new branch' %
+                    branch.name)
+                assert not has_seen_open_branch, (
+                    'Unexpected closed branch %s after open branch' %
+                    branch.name)
+                closed_branches.append(branch.name)
+                continue
 
-      if not options.leave_upstream:
-        if not has_seen_open_branch and len(closed_branches) > 0:
-          print(
-              'Setting upstream for first open branch %s to main'
-                  % branch.name)
-          set_upstream_for_current_branch_to_main()
+            if not options.leave_upstream:
+                if not has_seen_open_branch and len(closed_branches) > 0:
+                    print('Setting upstream for first open branch %s to main' %
+                          branch.name)
+                    set_upstream_for_current_branch_to_main()
 
-      has_seen_open_branch = True
-      has_seen_local_branch = has_seen_local_branch or (status == 'None')
+            has_seen_open_branch = True
+            has_seen_local_branch = has_seen_local_branch or (status == 'None')
 
-      if options.upload and status != 'closed':
-        if has_seen_local_branch:
-          print(
-              'Cannot upload branch %s since it comes after a local branch'
-                  % branch.name)
-        else:
-          upload_cmd = ['git', 'cl', 'upload', '-m', options.message]
-          if options.bypass_hooks:
-            upload_cmd.append('--bypass-hooks')
-          utils.RunCmd(upload_cmd, quiet=True)
+            if options.upload and status != 'closed':
+                if has_seen_local_branch:
+                    print(
+                        'Cannot upload branch %s since it comes after a local branch'
+                        % branch.name)
+                else:
+                    upload_cmd = ['git', 'cl', 'upload', '-m', options.message]
+                    if options.bypass_hooks:
+                        upload_cmd.append('--bypass-hooks')
+                    utils.RunCmd(upload_cmd, quiet=True)
 
-    if get_delete_branches_option(closed_branches, options):
-      delete_branches(closed_branches)
+        if get_delete_branches_option(closed_branches, options):
+            delete_branches(closed_branches)
 
-    utils.RunCmd(['git', 'cl', 'issue'])
+        utils.RunCmd(['git', 'cl', 'issue'])
+
 
 def delete_branches(branches):
-  assert len(branches) > 0
-  cmd = ['git', 'branch', '-D']
-  cmd.extend(branches)
-  utils.RunCmd(cmd, quiet=True)
+    assert len(branches) > 0
+    cmd = ['git', 'branch', '-D']
+    cmd.extend(branches)
+    utils.RunCmd(cmd, quiet=True)
+
 
 def get_branch_with_name(name, branches):
-  for branch in branches:
-    if branch.name == name:
-      return branch
-  return None
+    for branch in branches:
+        if branch.name == name:
+            return branch
+    return None
+
 
 def get_delete_branches_option(closed_branches, options):
-  if len(closed_branches) == 0:
-    return False
-  if options.leave_upstream:
-    return False
-  if options.delete == 'y':
-    return True
-  if options.delete == 'n':
-    return False
-  assert options.delete == 'ask'
-  print('Delete closed branches: %s (Y/N)?' % ", ".join(closed_branches))
-  answer = sys.stdin.read(1)
-  return answer.lower() == 'y'
+    if len(closed_branches) == 0:
+        return False
+    if options.leave_upstream:
+        return False
+    if options.delete == 'y':
+        return True
+    if options.delete == 'n':
+        return False
+    assert options.delete == 'ask'
+    print('Delete closed branches: %s (Y/N)?' % ", ".join(closed_branches))
+    answer = sys.stdin.read(1)
+    return answer.lower() == 'y'
+
 
 def get_status_for_current_branch(current_branch):
-  if current_branch.name == 'main':
-    return 'main'
-  return utils.RunCmd(['git', 'cl', 'status', '--field', 'status'], quiet=True)[0].strip()
+    if current_branch.name == 'main':
+        return 'main'
+    return utils.RunCmd(['git', 'cl', 'status', '--field', 'status'],
+                        quiet=True)[0].strip()
+
 
 def is_root_branch(branch, options):
-  return branch.name == options.from_branch or branch.upstream is None
+    return branch.name == options.from_branch or branch.upstream is None
+
 
 def pull_for_current_branch(branch, options):
-  if branch.name == 'main' and options.skip_main:
-    return
-  rebase_args = ['--rebase'] if options.rebase else []
-  utils.RunCmd(['git', 'pull'] + rebase_args, quiet=True)
+    if branch.name == 'main' and options.skip_main:
+        return
+    rebase_args = ['--rebase'] if options.rebase else []
+    utils.RunCmd(['git', 'pull'] + rebase_args, quiet=True)
 
 
 def set_upstream_for_current_branch_to_main():
-  utils.RunCmd(['git', 'cl', 'upstream', 'main'], quiet=True)
+    utils.RunCmd(['git', 'cl', 'upstream', 'main'], quiet=True)
+
 
 # Parses a line from the output of `git branch -vv`.
 #
@@ -203,29 +227,30 @@
 #     feature_prereq_a xxxxxxxxx [main: ...] ...
 #     main             xxxxxxxxx [origin/main] ...
 def parse(line):
-  is_current = False
-  if line.startswith('*'):
-    is_current = True
-    line = line[1:].lstrip()
-  else:
-    line = line.lstrip()
+    is_current = False
+    if line.startswith('*'):
+        is_current = True
+        line = line[1:].lstrip()
+    else:
+        line = line.lstrip()
 
-  name_end_index = line.index(' ')
-  name = line[:name_end_index]
-  line = line[name_end_index:].lstrip()
+    name_end_index = line.index(' ')
+    name = line[:name_end_index]
+    line = line[name_end_index:].lstrip()
 
-  if '[' in line:
-    line = line[line.index('[')+1:]
+    if '[' in line:
+        line = line[line.index('[') + 1:]
 
-    if ':' in line:
-      upstream = line[:line.index(':')]
-      return Repo(name, is_current, upstream)
+        if ':' in line:
+            upstream = line[:line.index(':')]
+            return Repo(name, is_current, upstream)
 
-    if ']' in line:
-      upstream = line[:line.index(']')]
-      return Repo(name, is_current, upstream)
+        if ']' in line:
+            upstream = line[:line.index(']')]
+            return Repo(name, is_current, upstream)
 
-  return Repo(name, is_current, None)
+    return Repo(name, is_current, None)
+
 
 if __name__ == '__main__':
-  sys.exit(main(sys.argv[1:]))
+    sys.exit(main(sys.argv[1:]))