class_docstr: Start node for a set of Streams
  
  Source nodes emit data into other nodes. They typically get this data
  by polling external sources, and are necessarily run by an event loop.
  
  Parameters
  ----------
  start: bool
      Whether to call the run method immediately. If False, nothing
      will happen until ``source.start()`` is called.
class_docstr_tok: ["Start","node","for","a","set","of","Streams","Source","nodes","emit","data","into","other","nodes",".","They","typically","get","this","data","by","polling","external","sources",",","and","are","necessarily","run","by","an","event","loop",".","Parameters","--","--","--","--","--","start",":","bool","Whether","to","call","the","run","method","immediately",".","If","False",",","nothing","will","happen","until","``","source.start","(",")","``","is","called","."]
docstr: set self.stopped, which will cause polling to stop after next run
docstr_tok: ["set","self.stopped",",","which","will","cause","polling","to","stop","after","next","run"]
code: def stop(self):
      """set self.stopped, which will cause polling to stop after next run"""
      if not self.stopped:
          self.stopped = True
  
imports: import asyncio
  from glob import glob
  import queue
  import os
  import time
  from tornado import gen
  import weakref
  from .core import Stream, convert_interval, RefCounter, sync
label_desc: Use image node_id 2 for calling the Source obj's underlying member method code with example usage: obj.stop() without return types