Diagram
The diagram:
Is generated by 7 lines of Markdown:
```pikchr
arrow right 200% "Markdown" "Source"
box rad 10px "Markdown" "Formatter" "(mdbook)" fit
arrow right 200% "HTML+SVG" "Output"
arrow <-> down 70% from last box.s
box same "Pikchr" "Preprocessor" "(mdbook-pikchr)" fit
```