def save_subjects(bill, subjects):
  #TODO fix duplicate subjects
  for subject_name in subjects:
    subject = Subject.objects.filter(name=subject_name)
    # If this subject is not in the db, add her/him
    if not subject:
      subject = Subject()
      subject.name = subject_name
      subject.save()
      # Associate this subject with imported bill
      subject.bills.add(bill)
      subject.save()
def create(subject_name, bill_id):
  subject = Subject.objects.filter(name = subject_name)

  if subject:
    subject[0].bills.add(Bill.objects.get(id = bill_id))
    return subject[0]

  else:
    subject = Subject()
    subject.name = subject_name
    subject.save()

    subject.bills.add(Bill.objects.get(id = bill_id))
    subject.save()
    return subject