Another key observation from the article is the clock adjustment process:
when you see a nearby firefly flash, nudge your clock a little bit forward.
We can use light sensor on the Circuit Playground Express to detect a nearby flash.
We can use the on light bright event to add code that will run when a bright light is detected. When this happens, we bump the clock and play a sound... unless we are also flashing (and clock is greater or equal to 8)!