public AndSpecification(Specification <T> spec2, Specification <T> spec1)
 {
     _spec2 = spec2;
     _spec1 = spec1;
 }
 public EqualSpecification(Specification <T> spec1, Specification <T> spec2, bool equality)
 {
     this._spec1    = spec1;
     this._spec2    = spec2;
     this._equality = equality;
 }