How to use the gftools.fonts_public_pb2.FamilyProto function in gftools

def main():
    args = parser.parse_args()
    response = requests.get(API_URL.format(args.key))
    try:
        webfontList = response.json()['items']
        webfontListFamilyNames = [item['family'] for item in webfontList]
    except (ValueError, KeyError):
        sys.exit("Unable to load and parse"
                 " list of families from Google Web Fonts API.")

    for dirpath, dirnames, filenames in os.walk(args.repo):
        metadata_path = os.path.join(dirpath, 'METADATA.pb')
        if not os.path.exists(metadata_path):
            continue

        metadata = FamilyProto()
        text_data = open(metadata_path, "rb").read()
        text_format.Merge(text_data, metadata)
        try:
            family = metadata.name
        except KeyError:
            print(('ERROR: "{}" does not contain'
                   ' familyname info.').format(metadata_path),
                  file=sys.stderr)
            continue

        try:
            index = webfontListFamilyNames.index(family)
            webfontsItem = webfontList[index]
        except ValueError:
            print(('ERROR: Family "{}" could not be found'
                   ' in Google Web Fonts API.').format(family))

Args:
    fontdir: Directory containing font files for which we want metadata.
  Returns:
    OrderedDict of a complete METADATA.pb structure.
  """
  file_family_style_weights = _FileFamilyStyleWeights(fontdir)

  first_file = file_family_style_weights[0].file
  subsets = ['menu'] + [s[0] for s in fonts.SubsetsInFont(first_file,
                                                          FLAGS.min_pct,
                                                          FLAGS.min_pct_ext)]
  old_metadata_file = os.path.join(fontdir, 'METADATA.pb')

  font_license = fonts.LicenseFromPath(fontdir)

  metadata = fonts_pb2.FamilyProto()
  metadata.name = file_family_style_weights[0].family

  if FLAGS.update and os.path.isfile(old_metadata_file):
    old_metadata = fonts_pb2.FamilyProto()
    with open(old_metadata_file, "rb") as old_meta:
      text_format.Parse(old_meta.read(), old_metadata)
      metadata.designer = old_metadata.designer
      metadata.category = old_metadata.category
      metadata.date_added = old_metadata.date_added
  else:
    metadata.designer = 'UNKNOWN'
    metadata.category = 'SANS_SERIF'
    metadata.date_added = time.strftime('%Y-%m-%d')

  metadata.license = font_license
  subsets = sorted(subsets)

Python object loaded from METADATA.pb content.
  Raises:
    ValueError: if file_or_dir isn't a METADATA.pb file or dir containing one.
  """
  if (os.path.isfile(file_or_dir) and
      os.path.basename(file_or_dir) == 'METADATA.pb'):
    metadata_file = file_or_dir
  elif os.path.isdir(file_or_dir):
    metadata_file = os.path.join(file_or_dir, 'METADATA.pb')
    if not os.path.isfile(metadata_file):
      raise ValueError('No METADATA.pb in %s' % file_or_dir)
  else:
    raise ValueError(
        '%s is neither METADATA.pb file or a directory' % file_or_dir)

  msg = fonts_pb2.FamilyProto()
  with codecs.open(metadata_file, encoding='utf-8') as f:
    text_format.Merge(f.read(), msg)

  return msg

def get_FamilyProto_Message(path):
    message = FamilyProto()
    text_data = open(path, "rb").read()
    text_format.Merge(text_data, message)
    return message

"""
  file_family_style_weights = _FileFamilyStyleWeights(fontdir)

  first_file = file_family_style_weights[0].file
  subsets = ['menu'] + [s[0] for s in fonts.SubsetsInFont(first_file,
                                                          FLAGS.min_pct,
                                                          FLAGS.min_pct_ext)]
  old_metadata_file = os.path.join(fontdir, 'METADATA.pb')

  font_license = fonts.LicenseFromPath(fontdir)

  metadata = fonts_pb2.FamilyProto()
  metadata.name = file_family_style_weights[0].family

  if FLAGS.update and os.path.isfile(old_metadata_file):
    old_metadata = fonts_pb2.FamilyProto()
    with open(old_metadata_file, "rb") as old_meta:
      text_format.Parse(old_meta.read(), old_metadata)
      metadata.designer = old_metadata.designer
      metadata.category = old_metadata.category
      metadata.date_added = old_metadata.date_added
  else:
    metadata.designer = 'UNKNOWN'
    metadata.category = 'SANS_SERIF'
    metadata.date_added = time.strftime('%Y-%m-%d')

  metadata.license = font_license
  subsets = sorted(subsets)
  for subset in subsets:
    metadata.subsets.append(subset)

  for (fontfile, family, style, weight) in file_family_style_weights: