title: Create an empty Popen() object in Python?
body: <p>Is there any way to create an empty Popen() object, or perhaps some other way to solve what I'm trying to do.</p>
  
  <p>I'll give a code example to show what I'm trying to accomplish:</p>
  
  <pre><code>com = [["ls","/"],["wc"]]
  p = Popen(["echo"])
  for c in com:
       p = Popen(c, stdin=p.stdout,stdout=PIPE,stderr=PIPE)
  l = list(p.communicate())
  </code></pre>
  
  <p>I have a nested list containing system commands that I'd like to run, by iterating through the list, but for this to work p must of course exist at the start of the first iteration. I can solve this like I've done, by simpy issuing an echo, but I was wondering if there's a neater and more correct way?</p>