Function py_breit_wigner 

pub fn py_breit_wigner(
    tags: &Bound<'_, PyTuple>,
    mass: PyParameter,
    width: PyParameter,
    l: &Bound<'_, PyAny>,
    daughter_1_mass: &PyMass,
    daughter_2_mass: &PyMass,
    resonance_mass: &PyMass,
    barrier_factors: bool,
) -> PyResult<PyExpression>

Construct a relativistic Breit-Wigner amplitude.