docs: def write_default_config(self, filename):
          """Write the default config file.
          """
          try:
              with open(filename, 'wt') as file:
                  file.write(DEFAULT_CONFIG)
              return True
          except (IOError, OSError) as e:
              print('Error writing %s: %s' % (filename, e.strerror or e), file=sys.stderr)
              return False