code: def update_hash(a_hash, mv):
      
      if mv.labels:
          signing.add_dict_to_hash(a_hash, encoding.MessageToPyValue(mv.labels))
      money_value = mv.get_assigned_value(u'moneyValue')
      if money_value is not None:
          a_hash.update(b'\x00')
          a_hash.update(money_value.currencyCode.encode('utf-8'))
docs: Adds ``mv`` to ``a_hash``
  
      Args:
         a_hash (`Hash`): the secure hash, e.g created by hashlib.md5
         mv (:class:`MetricValue`): the instance to add to the hash