Function add_demand_constraints 

pub fn add_demand_constraints(
    problem: &mut RowProblem,
    asset: &AssetRef,
    commodity: &Commodity,
    time_slice_info: &TimeSliceInfo,
    demand: &DemandMap,
    activity_vars: &IndexMap<TimeSliceID, Col>,
)

Adds demand constraints to the problem.

Constrains supply to be less than or equal to demand. One inequality constraint is added per time-slice selection at the commodity’s balance level, capping the sum of activity (scaled by flow coefficients) to the total demand for that selection.