title: How to set kivy widget id from Python code file
body: <p>I need help assigning ids to new kivy widgets that are created from a python function</p>
  
  <p>I've tried :  </p>
  
  <pre><code>old = Label(id = 'old')
  </code></pre>
  
  <p>and :</p>
  
  <pre><code>old = Label()
  old.id = 'old'
  </code></pre>
  
  <p>but it doesn't seem to work because, whenever i try referencing the widgets, it gives me an error</p>