Modifying anchor tag class from none to active using selenium & python

Question

I am trying to modify the class of an anchor tag from none to "active". This is the html:

<li class="item-1">
  <a href="#" class="active">
  </a>
</li>
<li class="item-1">
  <a href="#" class="">
  </a>
</li>

How can i change the class of the first

element to nothing and the class of the second

element to "active" using selenium in Python?

I am looking for the following:

<li class="item-1">
  <a href="#" class="">
  </a>
</li>
<li class="item-1">
  <a href="#" class="active">
  </a>
</li>