Function py_helicity_combinations 

pub fn py_helicity_combinations(
    py: Python<'_>,
    spin_1: &Bound<'_, PyAny>,
    spin_2: &Bound<'_, PyAny>,
) -> PyResult<Vec<(Py<PyAny>, Py<PyAny>, Py<PyAny>)>>

Enumerate daughter helicity combinations.