title: How to change a list outside function without a = function(a,b)?
body: <pre><code>l = ["1","2"]
  e = "3"
  def add(e,s):
      s = s + [e]
      return s
  add(e,l)
  print(l)
  </code></pre>
  
  <p>Why doesn’t it print <code>['1','2','3']</code>?</p>