def alternating(n):
    for perm in variations(list(range(n)), n):
        p = Permutation(perm)
        if p.is_even:
            yield p
Subclasses have to override this method to implement the
dataset/ETHPy150Open sympy/sympy/sympy/combinatorics/generators.py/alternating--crossover with--dataset/ETHPy150Open hhstore/flask-annotated/flask-0.7/flask/views.py/View.dispatch_request