shell = {
const sel = d3.create("svg")
.attr("width", options.width)
.attr("height", options.height)
const container = sel.append("g")
.attr("id", "container").attr("transform", `translate(${options.margins.left}, ${options.margins.top})`)
return Object.assign(sel.node(), {
update: render.bind(container)
});
}