Add a histogram for the data to the axes.

def _histplot_op(values, values2, rotated, ax, hist_kwargs):
    """Add a histogram for the data to the axes."""
    if values2 is not None:
        raise NotImplementedError("Insert hexbin plot here")

    bins = hist_kwargs.pop("bins")
    if bins is None:
        bins = get_bins(values)
    ax.hist(values, bins=bins, **hist_kwargs)
    if rotated:
        ax.set_yticks(bins[:-1])
    else:
        ax.set_xticks(bins[:-1])
    if hist_kwargs["label"] is not None:
        ax.legend()
    return ax