old_contents: headers = []
  beamline_configs = []
  event_descriptors = []
  events = []
  
  
  def find2(header_id=None, scan_id=None, owner=None, start_time=None,
            beamline_id=None, end_time=None):
      return {'headers': headers, 'beamline_configs': beamline_configs,
              'event_descriptors': event_descriptors, 'events': events}
  
new_contents: from datetime import datetime as dt
  
  
  class DummyEventDescriptor(object):
      def __init__(self):
          self.keys = {'temp': {'source': 'PV:blah'},
                       'picture': {'source': 'CCD:blah',
                                   'external': 'FILESTORE!!!!'}}
  
  
  class DummyEvent(object):
      def __init__(self):
          self.ev_desc = DummyEventDescriptor()
          self.data = {'temp': {'value': 273, 'timestamp': None},
                       'picture': {'value': 'np.ones((10, 10))',
                                   'timestamp': None}}
          self.time = dt(2014, 01, 01, 1, 2, 3)
  
  
  def find(header_id=None, scan_id=None, owner=None, start_time=None,
           beamline_id=None, end_time=None):
      return 3 * [DummyEvent()]
  
subject: Update dummy MDS to use find and return a list of events.