chart = {
const svg = DOM.svg(width, height);
const grid = buildSVG(svg)
grid
.append("path")
.attr('d', (d, i) => `M${margins.left + xi(i)} ${margins.top}l0,${canvasHeight}`);
grid
.append("path")
.attr('d', (d, i) => `M${margins.left} ${margins.top + yi(i)}l${canvasWidth},0`);
return svg;
}