Shows both the OurBigBook code and its rendered output, e.g.:
\OurBigBookExample[[
Some `ineline` code.
]]
which renders as:
Some `ineline` code.
which renders as:Someineline
code.
Its input should be thought of as a literal code string, and it then injects the rendered output in the document.
This macro is used extensively in the OurBigBook documentation.