T2414.hs:9:13: error:
    • Couldn't match type ‘b0’ with ‘(Bool, b0)’
      Expected: b0 -> Maybe (Bool, b0)
        Actual: b0 -> Maybe b0
    • In the first argument of ‘unfoldr’, namely ‘Just’
      In the expression: unfoldr Just
      In an equation for ‘f’: f = unfoldr Just