I have three polygons with common borders.
I can’t figure out how to color only the inner half of the border.

For the moment I have:

data = [
        (gpd.read_file("shape1.shp"), "#f2a6a5"),
        (gpd.read_file("shape2.shp"), "#fbebc0"),
        (gpd.read_file("shape3.shp"), "#dacbab"),
    ]
    for poly, color in data:
        poly.boundary.plot(
            ax=ax,
            color=color,
            linestyle="solid",
            linewidth=6,
        )

so, I would like to color only the inner part of the border. This would allow to have a two-color border between two polygons.