docs: def add_transaction_clause(self, clause):
          """
          Adds a iff clause to this statement
  
          :param clause: The clause that will be added to the iff statement
          :type clause: TransactionClause
          """
          if not isinstance(clause, TransactionClause):
              raise StatementException('only instances of AssignmentClause can be added to statements')
          clause.set_context_id(self.context_counter)
          self.context_counter += clause.get_context_size()
          self.transactions.append(clause)