Python3 recursively multiply items in hierarchical list

Question

I have a list as follows:

list = [\'Item\', \'Qty\'], [\'2\', \'1\'], [\'3\', \'1\'], [\'4\', \'1\'], [\'4.1\', \'2\'], [\'4.2\', \'2\'], [\'4.3\', \'2\'], [\