Function find_exprs_in_exprs 

fn find_exprs_in_exprs<'a, F>(
    exprs: impl IntoIterator<Item = &'a Expr>,
    test_fn: &F,
) -> Vec<Expr>
where
    F: Fn(&Expr) -> bool,

Search the provided Expr’s, and all of their nested Expr, for any that pass the provided test. The returned Expr’s are deduplicated and returned in order of appearance (depth first).