code: public function indexOf($expressionOrColumn)
      {
          if ($expressionOrColumn instanceof ExpressionContract) {
              return $this->indexOfExpression($expressionOrColumn);
          }
          return $this->indexOfColumn($expressionOrColumn);
      }
docs: Finds the index of expression or column name
  
  @param \Versatile\Search\Contracts\Expression|string
  @return int
  @throws \OutOfBoundsException