function bars(scale) {
const margin = 10,
width = 100,
height = 60,
chart = svg`<svg width=${width + 2 * margin} height=${height + 2 * margin}>
<g transform="translate(${margin}, ${margin})">
<rect width=${width} height="${height}"
fill="none" stroke="black" stroke-width="0.5" />
<rect x="${scale("one")}" width=${scale.bandwidth()} height="${height}"
fill="red"/>
<rect x="${scale("two")}" width=${scale.bandwidth()} height="${height}"
fill="green"/>
<rect x="${scale("three")}" width=${scale.bandwidth()} height="${height}"
fill="blue" />
<rect x="${scale("four")}" width=${scale.bandwidth()} height="${height}"
fill="#777" />
</g></svg>`;
return chart;
}