def create_diff(object_a, object_b):
 changes = _create_diffs_for(pvector([]), object_a, object_b)
 return Diff(changes=changes)

def create_diff ( object_a , object_b ) : changes = _create_diffs_for ( pvector ( [ ] ) , object_a , object_b ) return Diff ( changes = changes )
constructs a diff from object_a to object_b .