Re-usable Supernodes -- multiple instances of same one can occur in stream but modifying it immediately modifies all instances. Like a callable Function/Subroutine/Macro in programming languages.

Often we want to perform the same set of operations ("sub-flow") in multiple places in the stream, e.g. for similar/parallel data either from different data sources, or destined for different output or export nodes.  It is essential that the *same* operations be performed in all those places, even after modifying that set of operations.  So we need a "Re-usable Supernode" identified by its globally-distinct Name (not allowed to conflict with another existing when renaming).  Multiple instances of same (same-named) Re-usable Supernode can be placed in multiple locations in the stream canvas or within other supernodes (re-usable or not), and each instance has its own input and output connectors, but when modifying the contents of this Re-usable Supernode, all instances having this same name change together simultaneously.   This is similar to the concept of a callable Function/Subroutine/Macro in programming languages, which can be invoked from multiple places.   Of course it would be useful to be able to search for and identify/highlight all other instances of such a supernode so that you can see all the instances where the changes will have an effect (even though some will be inside other supernodes).   As soon as you select an instance of a re-usable supernode, all the other instances of same (same-named) should highlight themselves, and any other supernodes (reusable or not) directly or indirectly containing other instances should highlight themselves in a special/slight distinct way, both on the canvas in in the Streams Tree panel on the right.  It would also be useful to have a panel containing a "palette" of all existing Re-usable Supernodes, from which they could be dragged onto the canvas as a new instance.  Ideally, it could be possible to organize and group these re-usable supernodes in their Palette panel to help find them.