NewLock creates a new Lock object from geven header.

NewOpLock creates a new Lock object from geven header in given op.

ConcurrentOpError means lock was already acquired by another node.

DuplicatedOpError means the operation with the same ID alredy had been running.

Lock is a lock for the PBM operation (e.g.

LockHeader describes the lock.

StaleLockError - the lock was already got but the operation seems to be staled (no hb from the node).