foo.py

from sportamor.logistics.models import *
from datetime import date, timedelta

max_age = date.today() - timedelta(days=30)
returns = Return.objects.filter(status=ReturnStatuses.PENDING).filter(date_created__gt=max_age)
for r in returns:
 o = r.order
 invoices = o.invoices.all()
 for i in invoices:
  #print("Invoice {:d}, pending return {:d} order {:d}: {:s}".format(i.id, r.id, o.id, str(r.date_created)))
  m = i.get_total_value()
  if type(m) is Money:
   if m.is_zero():
    print("Invoice {:d}, pending return {:d} order {:d}: {:s}".format(i.id, r.id, o.id, str(r.date_created)))
    print("{:d} This order invoice is zero and SHOULD BE SEALED, sealing".format(i.id))
  # else:
  # print("{:d} ok".format(i.id))
    #r.order.seal() 
  else:
   print("Odd, order invoice has no Money: {:}".format(m))