Tries to infer if the Series (usually leftmost column) should be the index_col

    >>> looks_like_index(pd.Series(np.arange(100)))
    True

def looks_like_index(series, index_names=('Unnamed: 0', 'pk', 'index', '')):
    """ Tries to infer if the Series (usually leftmost column) should be the index_col

    >>> looks_like_index(pd.Series(np.arange(100)))
    True
    """
    if series.name in index_names:
        return True
    if (series == series.index.values).all():
        return True
    if (series == np.arange(len(series))).all():
        return True
    if (
        (series.index == np.arange(len(series))).all() and
        str(series.dtype).startswith('int') and
        (series.count() == len(series))
    ):
        return True
    return False