-spec file_read(Filename) -> {ok, Header, Msgs} | {error, Reason}
             when
                 Filename :: file:name_all(),
                 Header :: proplists:proplist(),
                 Msgs :: proplists:proplist(),
                 Reason :: file:posix() | badarg | terminated | system_limit | po_parse_error.

-spec file_write(Filename, Pot, Language, Header, Msgs) -> ok | {error, Reason}
              when
                  Filename :: file:name_all(),
                  Pot :: boolean(),
                  Language :: string(),
                  Header :: proplists:proplist(),
                  Msgs :: proplists:proplist(),
                  Reason :: file:posix() | badarg | system_limit | unknown_language.