set abstract method
Sets key to value.
Returns 'OK' if successful. Throws a TRServerException if an error occurs.
Implementation
// Future<String> set(String key, String value);
Future<String?> set(
String key,
String value, {
bool nx = false,
bool xx = false,
bool get = false,
int? ex,
int? px,
int? exAt,
int? pxAt,
bool keepTtl = false,
});