src/Enum.php
static function findKey($value): ?string
    {
        return self::hasValue($value)
            ? self::$valueToKeyMap[static::class][$value]
            : null;
    }
static function findKey($value): ?string
    {
        return self::hasValue($value)
            ? self::$valueToKeyMap[static::class][$value]
            : null;
    }
static function findKey ( $ value ) : ? string { return self :: hasValue ( $ value ) ? self :: $ valueToKeyMap [ static :: class ] [ $ value ] : null ; }
Attempt to find a key by its value. Returns NULL on failure.
Attempt to find a key by its value . Returns NULL on failure .