File: struct {}

implement File {
   close:   extern fun()
   flush:   extern fun()
   lines:   extern fun()            -> fun
   read:    extern fun(...?)        -> ...?
   seek:    extern fun(str?, int?)  -> int?
   setvbuf: extern fun(str?, int?)
   write:   extern fun(...)
}

file := new File {}

file close()