airflow/utils/helpers.py
def chain(*tasks):
    """
    Given a number of tasks, builds a dependency chain.

    chain(task_1, task_2, task_3, task_4)

    is equivalent to

    task_1.set_downstream(task_2)
    task_2.set_downstream(task_3)
    task_3.set_downstream(task_4)
    """
    for up_task, down_task in zip(tasks[:-1], tasks[1:]):
        up_task.set_downstream(down_task)
def chain(*tasks):
    for up_task, down_task in zip(tasks[:-1], tasks[1:]):
        up_task.set_downstream(down_task)
def chain ( * tasks ) : for up_task , down_task in zip ( tasks [ : - 1 ] , tasks [ 1 : ] ) : up_task . set_downstream ( down_task )
Given a number of tasks, builds a dependency chain.

    chain(task_1, task_2, task_3, task_4)

    is equivalent to

    task_1.set_downstream(task_2)
    task_2.set_downstream(task_3)
    task_3.set_downstream(task_4)
Given a number of tasks builds a dependency chain .