static PerformanceCalculator CreatePerformanceCalculator(Invoice.Performance performance, Plays.Play play)
 {
     return(play.Type switch
     {
         "tragedy" => new TragedyCalculator(performance),
         "comedy" => new ComedyCalculator(performance),
         _ => throw new Exception($"Unknown type: {play.Type}")
     });
 protected PerformanceCalculator(Invoice.Performance performance)
 {
     Performance = performance;
 }
 public ComedyCalculator(Invoice.Performance performance)
     : base(performance)
 {
 }