docs: def transaction_type(self, value):
          """Set the TransactionType (with Input Validation)"""
          if value is not None:
              if value not in self.ALLOWED_TRANSACTION_TYPES:
                  raise AttributeError('%s transaction_type element must be one of %s not %s' % (
                      self.__class__.__name__, ','.join(self.ALLOWED_TRANSACTION_TYPES), value,))
          self._transaction_type = value