subprocess: unexpected keyword argument capture_output : <p>When executing <code>subprocess.run()</code> as given in the <a href="https://docs.python.org/3/library/subprocess.html#subprocess.run" rel="noreferrer">Python docs</a>, I get a TypeError:</p>

<pre><code>&gt;&gt;&gt; import subprocess
&gt;&gt;&gt; subprocess.run(["ls", "-l", "/dev/null"], capture_output=True)
Traceback (most recent call last):
  File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  File "/usr/lib/python3.6/subprocess.py", line 403, in run
    with Popen(*popenargs, **kwargs) as process:
TypeError: __init__() got an unexpected keyword argument 'capture_output'
</code></pre>

<p>I am running Python 3.6.6:</p>

<pre><code>$ python3 --version
Python 3.6.6
</code></pre>
