Lists and List Comprehensions

1. Using either Kapulet's or Haskell's list comprehension syntax, write an expression that transforms [3, 1, 0, 2] into [3, 3, 3, 1, 2, 2].

Here is a hint

Define a function dup (n, x) that creates a list of n copies of x. Then use list comprehensions to transform [3, 1, 0, 2] into [[3, 3, 3], [1], [], [2, 2]]. Then use join to "flatten" the result.