code: function renderVerbs(verbs) {
      // For each new verb we add an LI and inside a link to show/hide and a span
      // to show the color-coded verb name.
      var list = d3.select("#verbs"),
          selection = list.selectAll("li").data(verbs),
          li = selection.enter().append("li");
      li.append("a")
        .attr("class", "show")
        .on("click", function(verb) {
          d3.event.stopPropagation();
          // If the class is "show", we're showing the verb. Flip class to hide
          // and turn verbsShowing off.
          if (this.className == "show") {
            this.className = "hide";
            verbsShowing[verb] = false;
          } else {
            this.className = "show";
            verbsShowing[verb] = true;
          }
          // Update all activities accordingly.
          renderActivities();
          return false;
        });
      li.append("span")
        .text(String)
        .style("background-color", function(verb) { return verbColor(verbs, verb) });
      selection.exit().remove();
    }
docs: Renders the verb selector: shows the msot popular verbs with option to show/hide each one.