Question

Loads a chunk using function func to get its pieces.
Each call to func must return a string that concatenates
with previous results.
A return of nil (or no value) signals the end of the chunk.

If there are no errors,
returns the compiled chunk as a function;
otherwise, returns nil plus the error message.
The environment of the returned function is the global environment.

chunkname is used as the chunk name for error messages
and debug information.