code: def git_hook(strict=False):
      diff_cmd = "git diff-index --cached --name-only --diff-filter=ACMRTUXB HEAD"
      files_modified = get_lines(diff_cmd)
      errors = 0
      for filename in files_modified:
          if filename.endswith('.py'):
              staged_cmd = "git show :%s" % filename
              staged_contents = get_output(staged_cmd)
              sort = SortImports(
                  file_path=filename,
                  file_contents=staged_contents.decode(),
                  check=True
              )
              if sort.incorrectly_sorted:
                  errors += 1
      return errors if strict else 0