old_contents: #!/usr/bin/python
  
  """
  Example of an Eliot action context spanning multiple threads.
  """
  
  from threading import Thread
  from sys import stdout
  
  from eliot import to_file, preserve_context, start_action
  to_file(stdout)
  
  
  def add_in_thread(x, y):
      with start_action(action_type="in_thread", x=x, y=y) as context:
          context.add_success_fields(result=x+y)
  
  
  with start_action(action_type="main_thread"):
      # Preserve Eliot context and restore in new thread:
      thread = Thread(target=preserve_context(add_in_thread),
                      kwargs={"x": 3, "y": 4})
      thread.start()
      # Wait for the thread to exit:
      thread.join()
  
  
new_contents: #!/usr/bin/env python
  
  """
  Example of an Eliot action context spanning multiple threads.
  """
  
  from __future__ import unicode_literals
  
  from threading import Thread
  from sys import stdout
  
  from eliot import to_file, preserve_context, start_action
  to_file(stdout)
  
  
  def add_in_thread(x, y):
      with start_action(action_type="in_thread", x=x, y=y) as context:
          context.add_success_fields(result=x+y)
  
  
  with start_action(action_type="main_thread"):
      # Preserve Eliot context and restore in new thread:
      thread = Thread(target=preserve_context(add_in_thread),
                      kwargs={"x": 3, "y": 4})
      thread.start()
      # Wait for the thread to exit:
      thread.join()
  
  
subject: Fix hashbang, add future import.