A context representing serialization of many objects to a single output stream.

The serialization library obtains an instance by calling serialization() and then uses references() to traverse the instances reachable from the instance(s) being serialized.

It is the serialization library's responsibility to manage object identity and handle cycles in the graph of object references. For example a serialization library that produced a hierarchical format might ignore identity when an instance is encountered multiple times (resulting in duplicate subtrees in the output), and simply throw an exception if it encountered a cycle.