reference to the *kwargs* which we use
    for this comparison.  If any of the values in *kwargs* are
    mutable we will not detect the case where they are mutated.
    In these cases we suggest using `.Figure.add_subplot` and the
    explicit Axes API rather than the implicit pyplot API.

    See Also
    --------
    .Figure.add_subplot
    .pyplot.subplots
    .pyplot.axes
    .Figure.subplots

    Examples
    --------
    ::

        plt.subplot(221)

        # equivalent but more general
        ax1 = plt.subplot(2, 2, 1)

        # add a subplot with no frame
        ax2 = plt.subplot(222, frameon=False)

        # add a polar subplot
        plt.subplot(223, projection='polar')

        # add a red subplot that shares the x-axis with ax1
        plt.subplot(224, sharex=ax1, facecolor='red')

        # delete ax2 from the figure
        plt.delaxes(ax2)

        # add ax2 to the figure again
        plt.subplot(ax2)

        # make the first axes "current" again
        plt.subplot(221)

    Ú
projectionÚ