Optional vector: Map<string, bigint>Private vectorafterOrEqual returns vector[other.actorID] is greaterOrEqual than given ticket's lamport
deepcopy returns a deep copy of this VersionVector.
filter returns new version vector consist of filter's actorID.
max returns new version vector which consists of max value of each vector
VersionVectoris a vector clock that is used to detect the relationship between changes whether they are causally related or concurrent. It is similar to vector clocks, but it is synced with lamport timestamp of the change.