Right to Left Right to Left

"For centuries, left-handers have suffered unfair discrimination in a world designed for right-handers."
Santrock, John W. (2008). Motor, Sensory, and Perceptual Development.

"Most humans (say 70 percent to 95 percent) are right-handed, a minority (say 5 percent to 30 percent) are left-handed, and an indeterminate number of people are probably best described as ambidextrous."
Scientific American. www.scientificamerican.com

One of the robots is charged with a simple task: to join a sequence of strings into one sentence to produce instructions on how to get around the ship. But this robot is left-handed and has a tendency to joke around and confuse its right-handed friends.

You are given a sequence of strings. You should join these strings into chunk of text where the initial strings are separated by commas. As a joke on the right handed robots, you should replace all cases of the words "right" with the word "left", even if it's a part of another word. All strings are given in lowercase.

Input: A sequence of strings as a tuple of strings (unicode).

Output: The text as a string.


left_join(("left", "right", "left", "stop")) == "left,left,left,stop"
left_join(("bright aright", "ok")) == "bleft aleft,ok"
left_join(("brightness wright",)) == "bleftness wleft"
left_join(("enough", "jokes")) == "enough,jokes"

How it is used: This is a simple example of operations using strings and sequences.

0 < len(phrases) < 42