title: Can provide an open file description/socket ID directly to a subprocess
body: <p>I'd like for Python to open a socket, but to provide that socket to a subprocess to read.
  For boring reasons, I'd prefer it if Python never had to read from the socket after opening the connection.</p>
  <p>For example --- is it possible to do something like this:</p>
  <pre><code>socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
      s.connect((HOST, PORT))
        # Just guessing here
      os.openSubProcess(&quot;myprocess&quot;, stdin=s.kernalSocketID)
      ...
  </code></pre>
  <p>I only care about Unix-land here.</p>