Problem extracting individual elements from pmt list and pmt dictionary messages

Hello GNURadio Community, 

I am creating a Python OOT block to send/receive pmt list and pmt dictionary messages. In both cases, I am having problems extracting the elements in the message. Let's assume (some trivial values):

P_list = pmt.to_pmt([1, 2, 3.45, 'eggs'])

P_dict = pmt.to_pmt({'spam': 20, 'eggs': 40})

How do I extract individual elements from P_list and P_dict? Nothing I tried worked.

I appreciate any help.

Regards,

George