code: function formatPct(sign, pct) {
    var rendered = (sign ? pct : Math.abs (pct)).toLocaleString ('en', {
      minimumIntegerDigits: 3,
      minimumFractionDigits: 1,
      maximumFractionDigits: 1,
      useGrouping: false
    });
    return (sign && pct >= 0 ? '+' + rendered : rendered) + '%';
  }
docs: formatPct :: (Boolean, Number) -> String