def get_base_layout(figs):
    """
    Generates a layout with the union of all properties of multiple
    figures' layouts

    Parameters:
    -----------
        fig : list(Figures)
            List of Plotly Figures
    """
    layout = {}
    for fig in figs:
        if not isinstance(fig, dict):
            fig = fig.to_dict()
        for k, v in list(fig['layout'].items()):
            layout[k] = v
    return layout