def __init__(self, name, filename=None):
        self.name = name
        super(NamedRequirements, self).__init__(filename=filename)
def f(i):
        start = W[i]
        extent = W[i + 1] - W[i]
        rv = te.reduce_axis((0, extent))
        return te.sum(X[rv + start], axis=rv)