code: public static Expression distinct(Val<Expression>[] args) {
          boolean dis = true;
          if (args.length > 1) {
              Object o = args[0].object();
              if (o instanceof Boolean || o instanceof BigDecimal) {
                  dis = args[0].bool();
              }
          }
          return new DistinctExpression(dis);
      }
docs: <p>distinct.</p>
  
  @param args an array of {@link ameba.db.dsl.QueryExprMeta.Val} objects.
  @return a {@link io.ebean.Expression} object.