* Only at load time, the value is decided, so do not statically optimize
for "__package__" as it is subject to change in those cases.
* Also, do not assign module attributes in the node tree, merely have
special references for them, generated in case of no other assignment
being seen. This affects "__loader__" and "__spec__" mostly
* The new nodes were moved to a new nodes module, along with the node
that handles "__file__" already.
