title: Opposite to capitalize for Python strings
body: <p>If I want to make a string start with a capital letter, I do</p>
  
  <pre class="lang-py prettyprint-override"><code>"hello world".capitalize()  # produces 'Hello world'
  </code></pre>
  
  <p>However, I would need the exact opposite: I need to make a string start with a lowercase letter, therefore something like this:</p>
  
  <pre class="lang-py prettyprint-override"><code>"Hello world".decapitalize()  # produces 'hello world'
  "HELLO WORLD".decapitalize()  # produces 'hELLO WORLD'
  </code></pre>
  
  <p>Do we have such a function/method in Python, or it needs to be coded from scratch?</p>