'Control' and 'variable' symbols in Sketch

This is a free download Sketch file to demonstrate a tutorial article titled 'Harness the power of symbols'. It shares how to use nested symbols (and what I call 'control symbols') to good effect for design system components. It also shares a process I use for system (web & product) design, whereby I use nested symbols much like Sass variables to quickly make bulk changes to multiple symbols.

Please read the tutorial, then download the Sketch file here. I hope it helps :)