//
// The hash function to use for sharding
func NewShardedConcurrentTxMap(initialCap int, hashfn HashFunc) ConcurrentTxMap {
concurrent_tx_map.go
cmap := new(ShardedConcurrentTxMap)
cmap.hashfn = hashfn
cmap.initialCap = max(nShards, initialCap/nShards)
return cmap
}
// Get returns the value corresponding to the key, if it exist