SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 4)
   ExpressionList (children 1)
    Function countSubstrings (children 1)
     ExpressionList (children 2)
      Function toString (children 1)
       ExpressionList (children 1)
        Identifier number
      Literal \'1\'
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier system.numbers
   Literal UInt64_9
   Literal UInt64_3