title: How to correctly define a function?
body: <p>In python I'm trying to do the following to define a function: </p>
  
  <pre><code>count_letters(word) = count_vowels(word) + count_consonants(word)
  </code></pre>
  
  <p>But for some reason, it is wrong. I'm getting this error:</p>
  
  <pre class="lang-none prettyprint-override"><code>SyntaxError: can't assign to function call
  </code></pre>
  
  <p>How can I fix it?</p>
  
  <p>Thank you</p>