SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 4)
   ExpressionList (children 1)
    Function count (children 1)
     ExpressionList
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier tab
   Function mapContainsKey (children 1)
    ExpressionList (children 2)
     Identifier map_fixed
     Function toFixedString (children 1)
      ExpressionList (children 2)
       Literal \'foo\'
       Literal UInt64_3
   Set