Checks whether a flake steps through a single-valued Property, whose retrieval addresses one value
and admits no collection constraints.
Cardinality is read off the property the branch steps through, never off range. The range
composes the cardinality of every step from the root, so it shows a single-valued property under a multi-valued
ancestor as multi-valued. A localised property counts as single-valued whatever its bounds, since it is retrieved
as one tag-keyed map (§5.4).
true if flake is a single-valued Property with a non-projected drain (or none); false
otherwise, including transform stages, Id / Type markers, collection,
and projected branches
Checks whether a flake steps through a single-valued Property, whose retrieval addresses one value and admits no collection constraints.
Cardinality is read off the property the branch steps through, never off range. The range composes the cardinality of every step from the root, so it shows a single-valued property under a multi-valued ancestor as multi-valued. A localised property counts as single-valued whatever its bounds, since it is retrieved as one tag-keyed map (§5.4).