
  [;1m-spec tl(List) -> term() when List :: nonempty_maybe_improper_list().[0m

  Returns the tail of [;;4mList[0m, that is, the list minus the first
  element, for example:

    > tl([geesties, guilies, beasties]).
    [guilies, beasties]

    > tl([geesties]).
    []

    > tl([geesties, guilies, beasties | improper_end]).
    [guilies, beasties | improper_end]

    > tl([geesties | improper_end]).
    improper_end

  Allowed in guard tests.

  Failure: [;;4mbadarg[0m if [;;4mList[0m is the empty list [;;4m[][0m.
