The example shows a reusable week selector widget that displays a current week number and lets users navigate between weeks 1 and 52 using left and right arrows. It renders three selectors at different sizes and positions to demonstrate scalability. The code uses D3 v4 with SVG, appending text elements for arrows and the week label. The `change_week` function updates the week, clamping it within the valid range, and `refresh_week` rebinds the data to update the displayed text. The widget is styled with monospace font and a `noselect` class to prevent text highlighting.