code: protected function buildOperatorCondition($operator, $condition, $attribute)
      {
          if (isset($this->queryOperatorMap[$operator])) {
              $operator = $this->queryOperatorMap[$operator];
          }
          return [$operator, $attribute, $this->filterAttributeValue($attribute, $condition)];
      }
docs: Builds an operator condition.
  @param string $operator operator keyword.
  @param mixed $condition attribute condition.
  @param string $attribute attribute name.
  @return array actual condition.