Map<K, V>.fromEntries constructor
Creates a new map and adds all entries.
Returns a new Map<K, V> where all entries of entries
have been added in iteration order.
If multiple entries have the same key,
later occurrences overwrite the earlier ones.
Implementation
factory Map.fromEntries(Iterable<MapEntry<K, V>> entries) =>
<K, V>{}..addEntries(entries);