public void bitcount(byte[] key, long start, long end) {
sendCommand(BITCOUNT, key, toByteArray(start), toByteArray(end));
}
public void bitop(BitOP op, byte[] destKey, byte[]... srcKeys) {
Keyword kw = Keyword.AND;
int len = srcKeys.length;
switch (op) {
case AND:
kw = Keyword.AND;
break;