Return `true` if the map contains a value corresponding to `key`.
(&self, key: K)
| 137 | |
| 138 | /// Return `true` if the map contains a value corresponding to `key`. |
| 139 | pub fn contains_key(&self, key: K) -> bool { |
| 140 | self.get(key).is_some() |
| 141 | } |
| 142 | |
| 143 | /// Insert a value into the map. |
| 144 | /// |