rotated,
                  an input to the top side has an angle of 3 (DOWN),
                  and an output from the top side has an angle of 1 (UP).
                  If a flow has been skipped (because its magnitude is less
                  than *tolerance*), then its angle will be *None*.
        *tips*    (N, 2)-array of the (x, y) positions of the tips (or "dips")
                  of the flow paths.
                  If the magnitude of a flow is less the *tolerance* of this
                  `Sankey` instance, the flow is skipped and its tip will be at
                  the center of the diagram.
        *text*    `.Text` instance for the diagram label.
        *texts*   List of `.Text` instances for the flow labels.
        ========  =============================================================

        See Also
        --------
        Sankey.add
        r