I'm trying to make a list of certain number of different letters: e.g. 2 "a"s, 3 "b"s and 5 "c"s, giving a a b b b c c c c c. I know how many of each number I need, but can't work out how to put this information into generating a list of them. (I would eventually like to randomise this list, e.g. to give a b b c a c c b c, if there's a way of doing this all in one step that would be great)