Function expand_query_source 

pub fn expand_query_source(source: &str, queries: Option<&Value>) -> String

VAPP-190: a package binding <scheme>:<name>?query=<id>&<params> naming one of the package’s queries → the same source with that query, its ${param} templates filled from the other params, as q=<canonical JSON> (a kind param stays). Anything else is returned as written.