The application "foo" uses this plpythonu source code to read the custom variable foo.transaction_id.
I guess this is way too complicated.
How to shorten/simplify below lines?
txid_list = list(plpy.execute(
'''SELECT current_setting FROM current_setting('foo.transaction_id')'''))
txid_str = txid_list [0]['current_setting']
txid = int(txid_str)