create a project that alternates blinking two LEDs - a nee-naw if you like

[tanyafish]

A simple one, we need instructions and code to alternate blinking two external LEDs on an arduino (not using onboard LEDs).
Needs:

• a description of what the code will do and how to wire up the LEDs, including warnings to avoid magic blue smoke
• a wiring diagram
• the code to do the blinking, with clear comments to show what each piece of it does. If in doubt, overcomment!

[tanyafish]

Note: this can be done with a microbit or an arduino nano - make sure you check the equipment list in the main repository and only use physical items from there.

For microbit, use micropython and save as a .py file, and for the arduino use C++ and save as a .ino file.