In your code a is a string (the result of input()), and you compare it to the list networks, so this comparison is always False.
Perhaps you meant to test if a is in the networks list?
In that case use if a in networks instead of if a == networks.
This function will shuffle the input “in-place”, without making a copy. That means that if you have a sequence a then it will be re-ordered after a call to random.shuffle(a). But if you pass in a literal sequence (as in your example) you will have no way to view the result because there’s no reference to that list anymore.