Test: added before the D3.js snippet (using hard-coded HTML)

Test: added after the D3.js snippet (using hard-coded HTML)

Remark: the d3.select("body").append() command append new HTML elements considering the "current" state of the target element (in this case: body),
where by current we mean the HTML loaded just (and only) before the D3 script element. For this reason the position of the D3 script element in
the source HTML code does change the result!