Function perform_optimisation 

pub fn perform_optimisation(
    asset: &AssetRef,
    max_capacity: Option<AssetCapacity>,
    commodity: &Commodity,
    coefficients: &ObjectiveCoefficients,
    demand: &IndexMap<TimeSliceID, Flow>,
    time_slice_info: &TimeSliceInfo,
    sense: Sense,
) -> Result<ResultsMap>

Performs optimisation for an asset, given the coefficients and demand.

Will either maximise or minimise the objective function, depending on the sense parameter. The optimisation will use continuous or integer capacity variables depending on whether the asset has a defined unit size.