class_docstr: Messages from a running external process
  
  This doesn't work on Windows
  
  Parameters
  ----------
  cmd : list of str or str
      Command to run: program name, followed by arguments
  open_kwargs : dict
      To pass on the the process open function, see ``subprocess.Popen``.
  with_stderr : bool
      Whether to include the process STDERR in the stream
  start : bool
      Whether to immediately startup the process. Usually you want to connect
      downstream nodes first, and then call ``.start()``.
  
  Example
  -------
  >>> source = Source.from_process(['ping', 'localhost'])  # doctest: +SKIP
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code: def __init__(
      self,
      cmd,
      open_kwargs=None,
      with_stderr=False,
      with_end=True,
      **kwargs,
  ):
      self.cmd = cmd
      self.open_kwargs = open_kwargs or {}
      self.with_stderr = with_stderr
      self.with_end = with_end
      self.process = None
      super().__init__(**kwargs)
  
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 1 to create a new from_process object from inherited base classes: Source with example: obj = from_process(cmd, open_kwargs, with_stderr, with_end)