+= and -= expressions in Python (?) : <p>I am trying to follow the example in <a href="http://cs231n.github.io/neural-networks-case-study/#loss" rel="nofollow noreferrer">this post</a>, and it was going smoothly until I ran into the lines of code with <code>-=</code> and <code>+=</code> calls.</p>

<p>I believe this might be some sort of misprint in expressions that are supposed to update the object on the RHS of <code>=</code> according to some condition.</p>

<p>Unfortunately, interpreting this expression is key in getting what the code is doing, and guessing defeats the purpose.</p>

<p>Do these fragments of code or operators make any sense? </p>

<p>What was intended by the author?</p>
