Add an item between each item already in the list [duplicate]

Answer 1

li = ['a','b','c','d','e']
for i in xrange(len(li)-1,0,-1):
    li[i:i] = '-'

or

from operator import concat
seq = ['a','b','c','d','e']
print reduce(concat,[['-',x] for x in seq[1:]],seq[0:1])

or

li = ['a','b','c','d','e']
newli = li[0:1]
[ newli.extend(('-',x)) for x in li[1:]]