pub fn run_why(db_dir: &Path, a: &str, b: &str) -> Result<String, CliError>Expand description
Body of mushroomdb why <db> <a> <b>: every rule edge between two keys
with the evidence that derived it, or an honest note that there is none.
A key the store does not hold is an error (node key not found: <key>),
not an empty answer.
The reply is what the explain_association tool sends, framing line
included: the rule names and matched values are graph content.