Filters out toolboxes out of a list of plots to be able to compose
    them into a larger plot.

def filter_toolboxes(plots):
    """
    Filters out toolboxes out of a list of plots to be able to compose
    them into a larger plot.
    """
    if isinstance(plots, list):
        plots = [filter_toolboxes(plot) for plot in plots]
    elif hasattr(plots, 'children'):
        plots.children = [filter_toolboxes(child) for child in plots.children
                          if not isinstance(child, ToolbarBox)]
    return plots