def xcom_push(
            self,
            key,
            value,
            execution_date=None):

        if execution_date and execution_date < self.execution_date:
            raise ValueError(
                'execution_date can not be in the past (current '
                'execution_date is {}; received {})'.format(
                    self.execution_date, execution_date))

        XCom.set(
            key=key,
            value=value,
            task_id=self.task_id,
            dag_id=self.dag_id,
            execution_date=execution_date or self.execution_date)
Mapping to a join
dataset/ETHPy150Open airbnb/airflow/airflow/models.py/TaskInstance.xcom_push--crossover with--dataset/ETHPy150Open zzzeek/sqlalchemy/test/orm/test_mapper.py/MapperTest.test_mapping_to_join_exclude_prop