title: python 3.7.1 cannot append inline after split
body: <p>I am currently trying to participate in a few one-liner contests and I noticed some weird behaviour that make it hard.  </p>
  
  <p>this<br>
  <code>
  "a,b,c".split(",").append("d")
  </code><br>
  returns None, while this:<br>
  <code>
  l = "a,b,c".split(",")<br>
  l.append("d")
  </code><br>
  correctly returns ["a","b","c","d"]<br>
  Is it a known issue or is it normal behaviour? Documentation says that split returns a list of strings.<br>
  I am using python 3.7.1, version from October 22 in the Arch official repos.</p>