The concept of a checksum is based on object's property and would be returned as string, is same way python does it with hash(object) or class.__hash__()
- its attributes ( key - pair )
- its geometry
where OID value would not be considered, since the OID value is always unique.
This would allow to compare two graph elements in two graph layers, for example
if ce.computeChecksum( graphNodeFromLayer1 ) == \
ce.computeChecksum( graphNodeFromLayer2 ):