How to use the textfsm.clitable.CliTable function in textfsm

def __init__(self, index_file=None, template_dir=None):
    """Create new CLiTable object.

    Args:
      index_file: String, file where template/command mappings reside.
      template_dir: String, directory where index file and templates reside.
    """
    # pylint: disable=E1002
    super(CliTable, self).__init__()
    self._keys = set()
    self.raw = None
    self.index_file = index_file
    self.template_dir = template_dir
    if index_file:
      self.ReadIndex(index_file)