<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _hash(data):

 """ generate a hash from data object to be used as cache key """

    hash_algo = hashlib.new('md5')
    hash_algo.update(pickle.dumps(data))
    # prefix allows possibility of multiple applications
    # sharing same keyspace
    return 'esi_' + hash_algo.hexdigest()