def diffvalues(t1, t2, f):

    t1v = set(values(t1, f))
    t2v = set(values(t2, f))
    return t2v - t1v, t1v - t2v
Outer joins t1->t2,t3.
dataset/ETHPy150Open alimanfoo/petl/petl/util/misc.py/diffvalues--crossover with--dataset/ETHPy150Open zzzeek/sqlalchemy/test/sql/test_query.py/JoinTest.test_outerjoin_x2