What would be your preferred way to concatenate strings from a sequence such that between each two consecutive pair a comma is added. That is, how do you map, for instance, [ 'a', 'b', 'c' ]to 'a,b,c'? (The case [ s ] and  should be mapped to s and '', respectively.)
I usually end up using something like ''.join(map(lambda x: x+',',l))[:-1], but also feeling somewhat unsatisfied.
Edit: I'm both ashamed and happy that the solution is so simple. Obviously, I have hardly a clue as to what I'm doing. (I probably needed "simple" concatenation in the past and somehow memorised s.join([e1,e2,...]) as a shorthand for s+e1+e2+....)