code: protected function buildBlockCondition($operator, $condition)
      {
          if (isset($this->queryOperatorMap[$operator])) {
              $operator = $this->queryOperatorMap[$operator];
          }
          return [
              $operator,
              $this->buildCondition($condition),
          ];
      }
docs: Builds block condition, which consists of a single condition.
  It covers such operators as `not`.
  @param string $operator operator keyword.
  @param mixed $condition raw condition.
  @return array actual condition.