
[x] !! test for type change. Not covered. Have to delete + put.
[x] use 1! lock for put. It's OK for now
[o] fall back on regular json
[o] thread-safe
[o] readme : get_many example
[o] subdir for types (2 last ascii chars argh)
[o] need for a purge mecha
[o] work/msgs/.0/8811-2151883888-1260352977.0.json issue...

[ ] LRU ?

