nested data svg example

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

<body>
  <script>
	var data_lowest = [
			[{key:"Key1", values:["1a","1b","1c"]}],
			[{key:"Key2", values:["2a","2b","2c"]}, {key:"Key21", values:["21a","21b","21c"]},{key:"Key22", values:["22a","22b","22c"]}],
			[{key:"Key3", values:["3a","3b","3c"]}],
			[{key:"Key4", values:["4a","4b","4c"]},{key:"Key41", values:["41a","41b","41c"]}]
		];

var svg = d3.select("body").append("svg")
      .attr("width", 960)
      .attr("height", 500)

// console.log(data_lowest);
		var g = svg.selectAll("svg").data(data_lowest).enter()

g.selectAll("text").data(function(d) {return d}).enter()
						.append("text")
						.attr("x", 120)
						// Here is the Problem. I don't now how to elegant move elements in y direction 
    				// depending on previous elements. And also move following elements down.
						.attr("y", function(d,i) {return 100+i*20;})
    				.text(function(d, i) {
  									console.log(i, d.values.toString());
  									return d.values.toString();
								})
    				.attr("font-size", 24)
    				.attr("font-family", "monospace");

</script>
</body>

https://d3js.org/d3.v4.min.js