decrease the refcount.
Each thread having a refcount to the object can safely read from the object.
- but modifications made to the object should be preceeded with a
+ but modifications made to the object should be preceded with a
_get_writable() function call. This function will check the refcount of the
object and if the object is referenced by more than one instance, a copy is
made of the object that is then by definition only referenced from the calling