docs: def read_file(path, absolute=False, encoding='utf-8'):
      """
      Read the file at `path`. If `absolute` is True, use absolute path,
      otherwise path is assumed to be relative to Tarbell template root dir.
      
      For example:
  
      .. code-block:: html+jinja
      
          <div class="chapter">
              {{ read_file('_chapters/one.txt')|linebreaks }}
          </div>
      """
      site = g.current_site
      if not absolute:
          path = os.path.join(site.path, path)
  
      try:
          return codecs.open(path, 'r', encoding).read()
      except IOError:
          return None