old_contents: import logging
  import emission.core.wrapper.wrapperbase as ecwb
  
  class Place(ecwb.WrapperBase):
      props = {"user_id": ecwb.WrapperBase.Access.WORM, # start UTC timestamp (in secs)
               "enter_ts": ecwb.WrapperBase.Access.WORM,  # the timestamp of entry (in secs)
               "enter_fmt_time": ecwb.WrapperBase.Access.WORM, # formatted entry time in timezone of place
               "exit_ts": ecwb.WrapperBase.Access.WORM,        # the timestamp of exit (in secs)
               "exit_fmt_time": ecwb.WrapperBase.Access.WORM,  # formatted time in timezone of place
               "ending_trip": ecwb.WrapperBase.Access.WORM,  # the id of the trip just before this
               "starting_trip": ecwb.WrapperBase.Access.WORM,  # the id of the trip just after this
               "location": ecwb.WrapperBase.Access.WORM, # the location in geojson format
               "source": ecwb.WrapperBase.Access.WORM,   # the method used to generate this place
               "duration": ecwb.WrapperBase.Access.WORM}    # the duration for which we were in this place
  
      enums = {}
      geojson = ["location"]
  
      def _populateDependencies(self):
          pass
  
new_contents: import logging
  import emission.core.wrapper.wrapperbase as ecwb
  
  class Place(ecwb.WrapperBase):
      props = {"user_id": ecwb.WrapperBase.Access.WORM, # start UTC timestamp (in secs)
               "enter_ts": ecwb.WrapperBase.Access.WORM,  # the timestamp of entry (in secs)
               "enter_fmt_time": ecwb.WrapperBase.Access.WORM, # formatted entry time in timezone of place
               "exit_ts": ecwb.WrapperBase.Access.WORM,        # the timestamp of exit (in secs)
               "exit_fmt_time": ecwb.WrapperBase.Access.WORM,  # formatted time in timezone of place
               "ending_trip": ecwb.WrapperBase.Access.WORM,  # the id of the trip just before this
               "starting_trip": ecwb.WrapperBase.Access.WORM,  # the id of the trip just after this
               "location": ecwb.WrapperBase.Access.WORM, # the location in geojson format
               "source": ecwb.WrapperBase.Access.WORM,   # the method used to generate this place
               "duration": ecwb.WrapperBase.Access.WORM}    # the duration for which we were in this place
  
      enums = {}
      geojson = ["location"]
      nullable = ["enter_ts", "enter_fmt_time", "ending_trip", # for the start of a chain
                  "exit_ts", "exit_fmt_time", "starting_trip"] # for the end of a chain
  
      def _populateDependencies(self):
          pass
  
      def __getattr__(self, key):
          # TODO: If this is a recurring pattern, might want to support a "nullable" list as well
          if (key in self.nullable) and (key not in self):
              return None
          else:
              return super(Place, self).__getattr__(key)
  
subject: Support nullable fields in the place object