David  B.

Utilities, which can be used in other notebooks via import

Observable Utils

it may be good to point out that while the `chart` cell is just a variable name, it is referencing a DOM element (that has yet to be added to the DOM). Observable notices that the cell is returning a DOM element and adds it to the page for you.

Ian Johnson

Ian Johnson, I do not want to overwhelm the potential reader (who is not familiar with Observable) with  details, so, I will go ahead and remove `chart` name, but I will mention that Observable automatically detects and displays DOM elements