docs: def typed_subtopic_data(fc, subid):
      '''Returns typed subtopic data from an FC.'''
      # I don't think this code will change after we fix the data race bug. ---AG
      ty = subtopic_type(subid)
      data = get_unicode_feature(fc, subid)
      assert isinstance(data, unicode), \
          'data should be `unicode` but is %r' % type(data)
      if ty == 'image':
          img_data = get_unicode_feature(fc, subid + '|data')
          img = re.sub('^data:image/[a-zA-Z]+;base64,', '', img_data)
          img = base64.b64decode(img.encode('utf-8'))
          return data, img
      elif ty in ('text', 'manual'):
          return data
      raise ValueError('unrecognized subtopic type "%s"' % ty)