public SpecificationBase <T, TId> Or(SpecificationBase <T, TId> specification)
 {
     return(new OrSpecification <T, TId>(this, specification));
 }
 public SpecificationBase <T, TId> And(SpecificationBase <T, TId> specification)
 {
     return(new AndSpecification <T, TId>(this, specification));
 }