def _finish_plot(ax, names, legend_loc=None, no_info_message="No Information"):
    """show a message in the axes if there is no data (names is empty)
       optionally add a legend
       return Fase if names is empty, True otherwise"""
    if( not names ):
        ax.text(0.5,0.5, no_info_message,
                fontweight='bold', va='center', ha='center',
                transform=ax.transAxes)
        return False
    if( legend_loc is not None ):
        ax.legend(names, loc=legend_loc)
    return True