title: how to edit a permutation
body: <p>every number is a port.
  and the permutation gives me all possible routes but my starting port is always number 1,so out of all combinations i want the ones that start with 1.</p>
  <p>this is all i got so far</p>
  <pre><code>from itertools import permutations
  
  routes = permutations([1 , 2, 3 ,4 , 5])
  for i in list(routes):
        print(i)
  </code></pre>
  <p>is there a way to enable me to pick those specific combinations?</p>