1	import Base
2	import ../rose/type.bend as R
3	import ./edge/type.bend as E
4	
5	# A compound graph: a forest of rose trees (what contains what) plus edges between any two keys.
6	type Compound<-N: Data> is Data:
7	  Compound{roots: List<&2, R.Rose<N>>, edges: List<&2, E.Edge>}