'Return the current spot instance data feed subscription
associated with this account, if any.
:type dry_run: bool
:param dry_run: Set to True if the operation should not actually run.
:rtype: :class:`boto.ec2.spotdatafeedsubscription.SpotDatafeedSubscription`
:return: The datafeed subscription object or None'

def get_spot_datafeed_subscription(self, dry_run=False):

    params = {}
    if dry_run:
        params['DryRun'] = 'true'
    return self.get_object('DescribeSpotDatafeedSubscription', params, SpotDatafeedSubscription, verb='POST')
