'Get all the hashes for a given PDU.
Args:
txn (cursor):
event_id (str): Id for the Event.
Returns:
A dict of algorithm -> hash.'

def _get_event_reference_hashes_txn(self, txn, event_id):

    query = 'SELECT    algorithm,    hash    FROM    event_reference_hashes    WHERE    event_id    =    ?'
    txn.execute(query, (event_id,))
    return {k: v for (k, v) in txn}
