Construct a Fork filter with up to four forks.
Construct a Fork from range of filters
Increment the number of filters past us that we own
Write a portion of a message to this filter.
Start a new message. Must be closed by endMsg() before another message can be started.
Notify that the current message is finished; flush buffers and do end-of-message processing (if any).
Check whether this filter is an attachable filter.
This class represents a fork filter, whose purpose is to fork the flow of data. It causes an input message to result in n messages at the end of the filter, where n is the number of forks.