split_string.py join_string.py From https://www.hackerrank.com/challenges/python-string-split-and-join
>>> a = "this is a string"
>>> a = a.split(" ") # a is converted to a list of strings.
>>> print a
['this', 'is', 'a', 'string']
>>> a = "-".join(a)
>>> print a
this-is-a-string