(examples-for hesc

("escapes <"
 (hesc "x < y")
 "x &lt; y")

("escapes >"
 (hesc "x > y")
 "x &gt; y")

("escapes &"
 (hesc "x && y")
 "x &amp;&amp; y")

("escapes < & >"
 (hesc "<script>alert('x && y')</script>")
 "&lt;script&gt;alert('x &amp;&amp; y')&lt;/script&gt;")

("not very cleverly re-escapes escaped entities"
 (hesc "&lt;p&gt;hello Jack &amp; Jill")
 "&amp;lt;p&amp;gt;hello Jack &amp;amp; Jill"))