drupal-graphql / graphql

      }

      // Unary operators need a single value.

      else if (!empty($operator) && $this->isUnaryOperator($operator)) {

        if (empty($value) || count($value) > 1) {

          throw new Error(sprintf("Unary operators must be associated with a single value (field '%s').", $field));

        }

        // Pick the first item from the values.

        $value = reset($value);

      }

      // Range operators need exactly two values.

      else if (!empty($operator) && $this->isRangeOperator($operator)) {

        if (empty($value) || count($value) !== 2) {

          throw new Error(sprintf("Range operators must require exactly two values (field '%s').", $field));

        }

      }

      // Null operators can't have a value set.

      else if (!empty($operator) && $this->isNullOperator($operator)) {