def left_outer_join(*args, **kwargs):
    """Shortcut for a left outer join."""
    # The documentation says a Cascading RightJoin is a right inner join, but
    # that's not true, it's really an outer join as it should be.
    kwargs['joiner'] = cascading.pipe.cogroup.LeftJoin()
    if not 'declared_fields' in kwargs:
        kwargs['declared_fields'] = None
    return CoGroup(*args, **kwargs)
dataset/ETHPy150Open twitter/pycascading/python/pycascading/cogroup.py/left_outer_join/original