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diff --git a/tools/Scanner/Xml/Basic.lean b/tools/Scanner/Xml/Basic.lean
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+/-
+Copyright (c) 2021 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Author: Dany Fabian
+-/
+import Std.Data.TreeMap.Basic
+import Init.Data.Ord.String
+
+namespace Lean
+namespace Xml
+
+@[expose] def Attributes := Std.TreeMap String String
+instance : ToString Attributes := ⟨λ as => as.foldl (λ s n v => s ++ s!" {n}=\"{v}\"") ""⟩
+
+mutual
+inductive Element
+| Element
+  (name : String)
+  (attributes : Attributes)
+  (content : Array Content)
+
+inductive Content
+| Element (element : Element)
+| Comment (comment : String)
+| Character (content : String)
+deriving Inhabited
+end
+
+mutual
+private partial def eToString : Element → String
+| Element.Element n a c => s!"<{n}{a}>{c.map cToString |>.foldl (· ++ ·) ""}</{n}>"
+
+private partial def cToString : Content → String
+| Content.Element e => eToString e
+| Content.Comment c => s!"<!--{c}-->"
+| Content.Character c => c
+
+end
+instance : ToString Element := ⟨private_decl% eToString⟩
+instance : ToString Content := ⟨private_decl% cToString⟩