This method is used to set the padding value which is the size of the gap between the circular arcs o nthe boundary.
The left uses the default .03 and the right has padding 0.
Modified http://vizjs.org/viz.v1.1.0.min.js to a secure url
https://d3js.org/d3.v4.min.js
https://vizjs.org/viz.v1.1.0.min.js