sketch out the impl and theorem stmt for write under the new design
sketch out the impl and theorem stmt for write under the new design

because the new language does not have a Crash operation,
write returns a bool status, depending on whether the log
is full or not (but this is left unspecified in the spec,
so we can see if non-determinism can finally work out.)

still not quite sure about the nested separation logic..

mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl