code: def set_contourf_properties(stroke_width, fcolor, fill_opacity, contour_levels, contourf_idx, unit):
      
      return {
          "stroke": fcolor,
          "stroke-width": stroke_width,
          "stroke-opacity": 1,
          "fill": fcolor,
          "fill-opacity": fill_opacity,
          "title": "%.2f" % contour_levels[contourf_idx] + ' ' + unit
      }
docs: Set property values for Polygon.