mapKeys<K2> method
Returns a new map where all keys of this map are transformed by the given
f
function in respect to their values.
If multiple entries have the same key after transformation, later occurences overwrite the earlier ones.
Implementation
ImmortalMap<K2, V> mapKeys<K2>(K2 Function(K key, V value) f) =>
map((key, value) => MapEntry(f(key, value), value));