Insert element in Python list after every nth element

Question

Say I have a Python list like this:

letters = [\'a\',\'b\',\'c\',\'d\',\'e\',\'f\',\'g\',\'h\',\'i\',\'j\']

I want to insert an \'x\' after

Answer 1

l = ['a','b','c','d','e','f','g','h','i','j']
[ l.insert(n+(n+1)*i, 'x') for i in range(len(l)/n) ]
print l