Struct Analysis 

pub struct Analysis {
    pub tree: Value,
    pub data_refs: Vec<(String, usize, usize)>,
    pub unused_lets: Vec<(String, usize, usize)>,
}

A parse plus the source facts the linter needs: where every bare-identifier data-series reference sits, and which let bindings were never used.

Fields

tree: Value

data_refs: Vec<(String, usize, usize)>

Every Data reference: (name, line, col), in source order. Includes references inside let bindings (used or not).

unused_lets: Vec<(String, usize, usize)>

let bindings never substituted anywhere: (name, line, col).