title: Why is logical not after an addition syntactically invalid?
body: <p>Today, I noticed that <code>not True + 5</code> is syntactically valid but <code>5 + not True</code> isn't.
  The syntax error points to the first character of not, as if the operator couldn't be used here. However, <code>5 + (not True)</code> works, which leads me to believe it is a parser issue.</p>
  <p>Are there any reasons for this error?</p>
  <ul>
  <li>Is it a design decision taken by the language?</li>
  <li>Is it is a parser error, or a behaviour not defined by the language's rules?</li>
  </ul>
  <p>I couldn't find any resources concerning this case.</p>