pub fn collect_var_names(expr: &RcExpr) -> HashSet<InternedStr> {
    let mut collector = VarNameCollector::default();
    collector.visit_expr(expr);
    collector.vars
}
/// Collects unique variable names in an expression.
Collects unique variable names in an expression.
Collects unique variable names in an expression .
pub fn collect_var_names(expr: &RcExpr) -> HashSet<InternedStr> {
    let mut collector = VarNameCollector::default();
    collector.visit_expr(expr);
    collector.vars
}
pub fn collect_var_names ( expr : & RcExpr ) -> HashSet < InternedStr > { let mut collector = VarNameCollector :: default ( ) ; collector . visit_expr ( expr ) ; collector . vars }
Collects unique variable names in an expression.
Collects unique variable names in an expression .
expr
&RcExpr
expr
&RcExpr