SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function substring (children 1)
     ExpressionList (children 2)
      Literal \'foo\'
      Function plus (children 1)
       ExpressionList (children 2)
        Literal UInt64_1
        Literal UInt64_1