The code a report runs before the report is laid out: the setup every
report runs, then its data and its content as its definition makes them
or as its own code does (step_code(): the datasets it registers, its
ARD as ard, the code) – a table's ARD and its process_code
(normalization and rework; by default none: the table's plan normalizes
ard).
With nothing to make it, a TODO that stops. program_code() writes it
into the program, and fetch_ard() runs it to learn what the ARD holds.