def __init__(self, gtfs, start_time_ut, lat, lon, max_duration_ut, min_transfer_time=<NUM_LIT:30>,<EOL>shapes=True, walk_speed=<NUM_LIT:0.5>):
self.gtfs = gtfs<EOL>self.start_time_ut = start_time_ut<EOL>self.lat = lat<EOL>self.lon = lon<EOL>self.max_duration_ut = max_duration_ut<EOL>self.min_transfer_time = min_transfer_time<EOL>self.shapes = shapes<EOL>self.event_heap = None<EOL>self.walk_speed = walk_speed<EOL>self._uninfected_stops = None<EOL>self._stop_I_to_spreading_stop = None<EOL>self._initialized = False<EOL>self._has_run = False<EOL>
Parameters
----------
gtfs: GTFS
    the underlying GTFS (database) connection for getting data
start_time_ut: number
    Start time of the spreading.
lat: float
    latitude of the spreading seed location
lon: float
    longitude of the spreading seed location
max_duration_ut: int
    maximum duration of the spreading process (in seconds)
min_transfer_time : int
    minimum transfer time in seconds
shapes : bool
    whether to include shapes