pub fn path_filter<S: BuildHasher>(
args: &HashMap<String, Value, S>
) -> TeraResult<Value>
Add a new filter to Tera templates:
path() sanitizes a string so that it can be used
to assemble filenames or paths.
path(alpha=true) prepends an apostroph when the result
starts with a number. This way we guaranty that the filename
never starts with a number. We do not allow this, to be able
to distinguish reliably the sort tag from the filename.