This fully working music sequencer took about 5 minutes to create using VizHub's "Edit with Code" feature. It even wrote the README content below!

Piano Sequencer

An interactive piano sequencer you can play and program!

Features:

• Interactive piano keyboard
• 8-step sequencer grid
• Adjustable tempo
• Play/stop controls

Based on the original piano app: https://github.com/curran/piano-app

How to Use

1. Click on the sequencer grid cells to activate/deactivate notes
2. Adjust the tempo using the slider
3. Press Play to start the sequence
4. You can also click on piano keys to play them directly