def cardioid(theta, a=1.0, k=1.0):
    return np.abs( a + a * np.cos(k*theta) )
Ensures @xframe_options_exempt properly instructs the
dataset/ETHPy150Open python-acoustics/python-acoustics/acoustics/directivity.py/cardioid--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/tests/regressiontests/decorators/tests.py/XFrameOptionsDecoratorsTests.test_exempt_decorator