code: public Attribute attribute(final String _alias)
          throws EFapsException
      {
          initialize(true);
          Attribute ret = null;
          final Optional<Select> selectOpt = this.selection.getSelects()
                          .stream()
                          .filter(select -> _alias.equals(select.getAlias()))
                          .findFirst();
          if (selectOpt.isPresent()) {
              ret = attribute(selectOpt.get());
          }
          return ret;
      }
docs: Attribute.
  
  @param _alias the alias
  @return the attribute
  @throws EFapsException the e faps exception