HH\Set::lastKey
Returns the last "key" in the current Set
public function lastKey(): ?arraykey;
Since Sets do not have keys, it returns the last value.
This method is interchangeable with lastValue().
Returns
Examples
This example shows that lastKey returns the last value in the Set. An empty Set will return null as its last key/value.
$s = Set {'red', 'green', 'blue', 'yellow'};
\var_dump($s->lastKey());
$s = Set {};
\var_dump($s->lastKey());