code: public function toArray()
      {
          $vars = get_object_vars($this);
          $vars['type'] = $this->getType();
  
          $queries = array();
          foreach ($vars as $k => $v) {
              if ($v !== null) {
                  $values = is_array($v) ? $v : array(':'=>$v);
                  foreach ($values as $matcher=>$value) {
                      $queries[] = $k . $matcher .  $value;
                  }
              }
          }
          return $queries;
      }
docs: property values can either be a scalar value or an array with ':', '<', or '>' as keys
  
  if it is a scalar value, it is assumed a ':'
  
  
  @return array