title: Is there any magic method for reflected augmented assignment?
body: <p>I have two user-defined classes, <code>a</code> and <code>b</code>. For such an augmented addition assignment between them:</p>
  <pre><code>a += b
  </code></pre>
  <p>Where <code>a</code> returns <code>NotImplemented</code> when it encounters <code>b</code>, is it expected that Python will look for a reflected augmented assignment in the other operand, i.e. <code>b</code>?</p>
  <p>(Edited in response to comments)</p>
  <p>I have noticed that already a slightly similar concept exists in some other magic methods, like <code>__format__(self, other)</code>:</p>
  <pre><code>&quot;A string {var:fmt_str}&quot;.format(var=b) === b.__format__(&quot;fmt_str&quot;)
  </code></pre>