Added the code for the single dispatch

fluent/chap.07/code/htmldispatch.py

@@ -0,0 +1,11 @@
+from functools import singledispatch
+import html
+from typing import Any
+
+# singledispatch marks the function that will handle the base type
+
+
+@singledispatch
+def htmlize(obj: Any):
+    content = html.escape(repr(obj))
+    return '<pre>{}</pre>'.format(content)