Function select_assets_for_single_market 

fn select_assets_for_single_market(
    model: &Model,
    commodity_id: &CommodityID,
    region_id: &RegionID,
    year: u32,
    demand: &IndexMap<(CommodityID, RegionID, TimeSliceID), Flow>,
    existing_assets: &[AssetRef],
    prices: &CommodityPrices,
    writer: &mut DataWriter,
) -> Result<Vec<AssetRef>>

Select assets for a single market in a given year

Returns a list of assets that are selected for investment for this market in this year.