Library for text substitutions with calculations?

[2QdxY4RzWzUUiLuE at potatochowder.com]

On 2020-12-15 at 16:04:55 +0100,
Jan Erik Moström <lists at mostrom.pp.se> wrote:

> I want to do some text substitutions but a bit more advanced than what
> string.Template class can do. I addition to plain text substitution I would
> like to be able to do some calculations:
> 
> $value+1 - If value is 16 this would insert 17 in the text. I would also
> like to subtract.

[...]

A lot of libraries for making web pages can do things like that; a
starting point is <https://wiki.python.org/moin/Templating>.

HTH,
Dan