devcard package provides Current function, which returns the devcard currently being filled with cells.

It point to the same devcard as the entry function parameter dc, as you can see:

dc.Ann("dc == devcard.Current()", dc == devcard.Current())

// dc == devcard.Current()
true

The reason it’s exposed is to make it available to any function in our program, no matter how deeply nested. This can be useful for occasional printf-style debugging or for some quick experiments.