code: func (n *BuilderNode) ResponsibleForReplicaPartition(replica, partition int) bool {
  	for _, partitionToNode := range n.builder.ring.ReplicaToPartitionToNode {
  		if int(partitionToNode[partition]) == n.index {
  			return true
  		}
  	}
  	return false
  }
docs: // ResponsibleForReplicaPartition returns true if this node is reponsible for
  // the specific replica and partition given.