How to parse xml file in variable-string?

Shell Programming and Scripting
1

In the wake of the post: how-parse-following-xml-file
Thank you for the very useful chakrapani response 302355585-post4 !

A close question.
How to pass a file to xmllint in variable?
For example, let it be:

NEARLY_FILE='<?xml version="1.0" encoding="iso-8859-1"?><html><set label="09/07/29" value="1241.90"/></html>'

Then I want to do something like this:

echo 'cat /html' | xmllint --shell $NEARLY_FILE

and get:

<html><set label="09/07/29" value="1241.90"/></html>

Thanks in advance!