This is a universal Python binding for the LMDB 'Lightning' Database.

LMDB is a tiny database with the following properties:
* Ordered map interface (keys are always lexicographically sorted).
* Reader/writer transactions: readers don’t block writers, writers don’t block readers. Each environment supports one concurrent write transaction.
* Cheap read transactions.
* Environments may be opened by multiple processes on the same host.
* Multiple named databases may be created with transactions covering all named databases.
* Memory mapped, allowing for zero copy lookup and iteration. This is optionally exposed to Python using the buffer() interface.
* Maintenance requires no external process or background threads.
* No application-level caching is required: LMDB uses the operating system’s buffer cache.