[Biopython] Need help in making a back table for the CodonTable object

[Alexander Castro]

Hello all, I apologize if this sound elementary but how can create a back table that will return more than one codon? For example, for table="Bacterial", codons CTT, CTG and CTA code for L (Lysine). How can I back out, given "L" get CTT, CTG and CTG. The back_table method only returns one value: output = bacterial_table.back_table["L"].
Any help would be greatly appreciated.
Regards,
Alexander Castro