public Athlete WithValidProperties(Athlete entity)
 {
     entity.FirstName = "Joe";
     entity.LastName = "Bloggs";
     entity.Id = 22;
     return entity;
 }
 public Athlete WithNameTonyAndValidProperties(Athlete entity)
 {
     entity.FirstName = "Tony";
     entity.Id = 88;
     return entity;
 }
 public Athlete WithTwoExtendsAttributes(Athlete entity)
 {
     return entity;
 }
 public Athlete WithInvalidProperties(Athlete entity)
 {
     entity.Id = 0;
     return entity;
 }