Challenge 1: fmap Over Just, Nothing, and a List — Possible Solution
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Main.hs:

main :: IO ()
main = do
  print (fmap (*2) (Just 21))
  print (fmap (*2) Nothing :: Maybe Int)
  print (fmap (*2) [1, 2, 3, 4])

Output:

    Just 42
    Nothing
    [2,4,6,8]

Explanation:
fmap (*2) (Just 21) applies the doubling function to the value INSIDE
the Just, producing Just 42 without any manual unwrapping. fmap (*2)
Nothing has nothing to apply the function to at all -- the function
is simply never called, and the result stays Nothing, exactly the
"safely does nothing" behavior the chapter describes. fmap (*2) over
the list doubles every element, the same behavior Haskell's own
built-in map would give for a plain list -- confirming fmap is a
genuine generalization, not a different behavior for lists
specifically.

WHY THIS WORKS AS AN ANSWER
------------------------------
This applies fmap to all three of the chapter's own example types
(Just, Nothing, and a list), demonstrating the "safely does nothing"
Nothing case explicitly rather than skipping it.