L.index(value, [start, [stop]]) -> integer -- return first index of value.
        Raises ValueError if the value is not present.

def index(self, value, start=None, stop=None):
        """
        L.index(value, [start, [stop]]) -> integer -- return first index of value.
        Raises ValueError if the value is not present.
        """
        if start is None:
            start = 0
        if stop is None:
            stop = len(self._col_list)
        return self._col_list.index(value, start, stop)