public PredicateBuilder <T> Or(Expression <Func <T, bool> > rigthExpression)
 {
     this.expression = PredicateExtensions.Or(this.expression, rigthExpression);
     return(this);
 }
 public PredicateBuilder(bool defaultExpression)
 {
     expression = defaultExpression ? PredicateExtensions.True <T>() : PredicateExtensions.False <T>();
 }