2 Checks for uses of `contains_key` + `insert` on `HashMap`
6 Using `entry` is more efficient.
9 The suggestion may have type inference errors in some cases. e.g.
11 let mut map = std::collections::HashMap::new();
12 let _ = if !map.contains_key(&0) {
21 if !map.contains_key(&k) {
27 map.entry(k).or_insert(v);