Function delta 

pub(crate) fn delta(
    axis: Named<RiskAxis>,
    basis: Named<Basis>,
    aggregation: Named<Aggregation>,
    scale: Option<Named<Scale>>,
) -> PyMeasure

The typed spelling of delta:<axis>[:<basis>[:<aggregation>]][:<scale>]: a first-order sensitivity on axis, against basis, collapsed by aggregation, in scale where one is stated. Each part takes its class or its string.