How to use the gftools.util.google_fonts.CodepointsInFont function in gftools

def main():
  if len(sys.argv) != 2 or sys.argv[1][-4:] != ".ttf":
    sys.exit('Usage: {} fontfile.ttf'.format(sys.argv[0]))

  expected = set()
  for nam_file in NAM_FILES:
    nam_filepath = os.path.join(NAM_DIR, nam_file)
    expected.update(CodepointsInNamelist(nam_filepath))

  filename = sys.argv[1]
  diff = expected - CodepointsInFont(filename)

  print(filename),
  if bool(diff):
    print('missing'),
    for c in sorted(diff):
      print('0x%04X' % (c)),
  else:
    print('OK')

def main(argv):
  if len(argv) != 2 or not os.path.isdir(argv[1]):
    sys.exit('Must have one argument, a directory containing font files.')

  dirpath = argv[1]
  cps = set()
  for f in _GetFontFiles(dirpath):
    cps.update(fonts.CodepointsInFont(os.path.join(dirpath, f)))

  for f in _GetFontFiles(dirpath):
    diff = cps - fonts.CodepointsInFont(os.path.join(dirpath, f))
    if bool(diff):
      print('%s failed' % (f))
      for c in diff:
        print('0x%04X' % (c))
    else:
      print('%s passed' % (f))

def _InconsistentSubsetSupport(file1, file2, subsetcps):
  """Returns difference in number of codepoints supported.

  Args:
    file1: Name of font file
    file2: Name of font file
    subsetcps: Complete set of codepoints to be supported
  Returns:
    Difference in number of codepoints between file1 and file2.
  """
  supportcps1 = len(subsetcps.intersection(fonts.CodepointsInFont(file1)))
  supportcps2 = len(subsetcps.intersection(fonts.CodepointsInFont(file2)))
  return abs(supportcps1 - supportcps2)

def DiffCoverage(font_filename1, font_filename2, subset):
  """Prints a comparison of the coverage of a given subset by two fonts.

  Args:
    font_filename1: The first font to compare.
    font_filename2: The second font to compare.
    subset: The lowercase name of the subset to compare coverage of.
  """
  f1cps = fonts.CodepointsInFont(font_filename1)
  f2cps = fonts.CodepointsInFont(font_filename2)

  if subset != 'all':
    subset_cps = fonts.CodepointsInSubset(subset)
    f1cps &= subset_cps
    f2cps &= subset_cps
  else:
    subset_cps = None

  subset_cp_str = ('/%d' % len(subset_cps)) if subset_cps is not None else ''

  print('  %s %+d (%d%s => %d%s)' % (
      subset, len(f2cps) - len(f1cps), len(f1cps), subset_cp_str, len(f2cps),
      subset_cp_str))

def _InconsistentSubsetSupport(file1, file2, subsetcps):
  """Returns difference in number of codepoints supported.

  Args:
    file1: Name of font file
    file2: Name of font file
    subsetcps: Complete set of codepoints to be supported
  Returns:
    Difference in number of codepoints between file1 and file2.
  """
  supportcps1 = len(subsetcps.intersection(fonts.CodepointsInFont(file1)))
  supportcps2 = len(subsetcps.intersection(fonts.CodepointsInFont(file2)))
  return abs(supportcps1 - supportcps2)

def DiffCoverage(font_filename1, font_filename2, subset):
  """Prints a comparison of the coverage of a given subset by two fonts.

  Args:
    font_filename1: The first font to compare.
    font_filename2: The second font to compare.
    subset: The lowercase name of the subset to compare coverage of.
  """
  f1cps = fonts.CodepointsInFont(font_filename1)
  f2cps = fonts.CodepointsInFont(font_filename2)

  if subset != 'all':
    subset_cps = fonts.CodepointsInSubset(subset)
    f1cps &= subset_cps
    f2cps &= subset_cps
  else:
    subset_cps = None

  subset_cp_str = ('/%d' % len(subset_cps)) if subset_cps is not None else ''

  print('  %s %+d (%d%s => %d%s)' % (
      subset, len(f2cps) - len(f1cps), len(f1cps), subset_cp_str, len(f2cps),
      subset_cp_str))