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 has (children 1)
    ExpressionList (children 2)
     Function mapValues (children 1)
      ExpressionList (children 1)
       Identifier map
     Literal \'foo\'
   Set