Extending forward-list to include multi-letter tags

[gnuist006]

I am sure this is a trivial problem for many of you, and it is one of
those problems that is like a mathematical puzzle with definite
solutions. I am interested in seeing multiple solutions to it.

Here is the problem:

The pair of functions forward-list and backward-list allow moving
the cursor to the next matching paren, bracket or brace. So it
works for characters like
{[(  )]}

The main utility of this function is mainly due to the nesting that
may be there, so a simple forward search wont take care of it.

Here, I would like to find out how one can find matching multi
letter tags.

For example, I have a tag like

<tag> and its matching tag is </tag>

there may be nested tags like this.

Essentially, the solution involves first finding the algorithm for
the forward-list and then extending it to multi-letter tags.

How can I get the lisp definition of a function inside emacs ?

I have posted this in cll and cls because their solutions may
be modified to work in emacs lisp.

Thanks to the star who can solve it.
gnuist