def execute_command(command: Command, cache: Cache) -> Union[str, bytes]:
args = command.args
result: Union[str, bytes] = _NOT_EXECUTED
if isinstance(command, CommandSet):
if cache.set_item(args[0], command.get_bytes_attachment(),
int(args[1])):
result = _SUCCESS
else:
result = _FAILURE
elif isinstance(command, CommandGet):
item = cache.get_item(args[0])
if item is None:
result = _NOT_FOUND
else:
result = str(len(item)).encode() + SEPARATOR_BINARY + item
elif isinstance(command, CommandDelete):
if cache.delete_item(args[0]):
result = _SUCCESS
else:
result = _FAILURE
if isinstance(result, str):
result += SEPARATOR
else:
result += SEPARATOR_BINARY
return result
