If the output of your cell is a generator object, it will get consumed automatically. If you scroll down to the part about generator functions in https://observablehq.com/@observablehq/introduction-to-generators#range the behavior is described.

Also see https://observablehq.com/@mbostock/custom-generators and https://observablehq.com/@observablehq/generator-cells-functions-and-objects

You might also enjoy https://observablehq.com/@jrus/itertools

Jacob Rus

Hey Jacob, Thanks for response. What do you mean by "gets consumed automatically" in the first link you provided, they define a generator function in the notebook and then calls that generator function. This returns the value "99". What happened to values 0-98. Were they run but not displayed?

It blew through all of the values 0–99 at lightning speed, yielding each one in turn, with 99 left at the end.

Try pressing shift-return while the cell is highlighted. You’ll see it go through all of the numbers again, for like 1 animation frame each.