[Biopython] accessing PDB IDcode when using PDBParser

[Mark Diekhans]

How does one access the idCode in the PDB HEADER when using the PDBParser?
I can't find this in the documentation or the code.

Also, what is function of the `id' argument for PDBParser.get_structure:
The documentation is just self-referential:
       o id - string, the id that will be used for the structure

Seems no obvious way via MMCIFParser either.

Thanks!