
  -type iolist() ::
            maybe_improper_list(byte() | binary() | iolist(),
                                binary() | []).

  A list containing bytes and/or iodata. This datatype is used to
  represent data that is meant to be output using any I/O module.
  For example: file:write/2 or gen_tcp:send/2.

  In most use cases you want to use iodata() instead of this type.
