function addLine(c, i) {
const path = d3.select(this);
const measure = d => d.confirmed.sma[1].value;
const y = d3.scaleLinear()
.domain(d3.extent(c.values, measure))
.range([height - margin.bottom, margin.top])
;
const line = d3.line()
.x(d => x(d.date))
.y(d => y(measure(d)))
.defined(measure)
;
path
.attr('d', line(c.values))
.attr('class', c.key.replace('/\s/g', '').toLowerCase())
;
}