code: protected function realCol(
          $col = '',
          /*# string */ $colAlias = '',
          $rawMode = false
      ) {
          // col array definition
          if (is_array($col)) {
              foreach ($col as $key => $val) {
                  if (is_int($key)) {
                      $key = $val;
                      $val = '';
                  }
                  $this->realCol($key, $val, $rawMode);
              }
  
          // clear columns
          } else if ('*' === $col) {
              $this->clause_column = [];
  
          // add columns
          } elseif (!empty($col)) {
              // auto raw mode detect
              $rawMode = $rawMode ?: $this->isRaw($col);
  
              if ('' === $colAlias) {
                  $this->clause_column[] = [$rawMode, $col];
              } else {
                  $this->clause_column[(string) $colAlias] = [$rawMode, $col];
              }
          }
          return $this;
      }
docs: {@inheritDoc}