SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 5)
    Function toTypeName (children 1)
     ExpressionList (children 1)
      Identifier a
    Function toTypeName (children 1)
     ExpressionList (children 1)
      Identifier b
    Function toTypeName (children 1)
     ExpressionList (children 1)
      Identifier c
    Function toTypeName (children 1)
     ExpressionList (children 1)
      Identifier d
    Function toTypeName (children 1)
     ExpressionList (children 1)
      Identifier f
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier set_null