SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 3)
    Function count (alias len) (children 1)
     ExpressionList (children 1)
      Identifier b
    Function substring (children 1)
     ExpressionList (children 3)
      Identifier a
      Literal UInt64_1
      Literal UInt64_3
    Function substring (children 1)
     ExpressionList (children 3)
      Identifier a
      Literal UInt64_1
      Identifier len
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier group_by_all