Partition shift value

The partition shift value is known internally to the Ring class as _part_shift. This value is used to shift an MD5 hash to calculate the partition where the data for that hash should reside. Only the top four bytes of the hash is used in this process. For example, to compute the partition for the /account/container/object path, the Python code might look like the following code:

partition = unpack_from('>I',
md5('/account/container/object').digest())[0] >>
self._part_shift

For a ring generated with part_power P, the partition shift value is 32 - P.