SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function indexOf (children 1)
     ExpressionList (children 2)
      Literal Array_[\'a\', \'b\', \'c\']
      Function toLowCardinality (children 1)
       ExpressionList (children 1)
        Literal \'a\'
