Whether to include the index item (and index_names item if `orient`
        is 'tight') in the returned dictionary. Can only be ``False``
        when `orient` is 'split' or 'tight'.

        .. versionadded:: 2.0.0

    Returns
    -------
    dict, list or collections.abc.Mapping
        Return a collections.abc.Mapping object representing the DataFrame.
        The resulting transformation depends on the `orient` parameter.
    z?DataFrame columns are not unique, some columns will be omitted.)