Removes
key
and its associated value, if present, from the map.
Returns the value associated with
key
before it was removed.
Returns
null
if
key
was not in the map.
Note that some maps allow
null
as a value,
so a returned
null
value doesn't always mean that the key was absent.
final terrestrial = <int, String>{1: 'Mercury', 2: 'Venus', 3: 'Earth'};
final removedValue = terrestrial.remove(2); // Venus
print(terrestrial); // {1: Mercury, 3: Earth}
