                        <span class="n">plot_axis_labels</span> <span class="o">=</span> <span class="n">plot_axis_labels</span><span class="p">,</span>
                                     <span class="n">hbin_color_map</span> <span class="o">=</span> <span class="n">hbin_color_map</span><span class="p">)</span>

    <span class="c1"># setup color map for plotting color shift vectors:</span>
    <span class="k">if</span> <span class="n">hvector_color_map</span> <span class="ow">is</span> <span class="kc">N