def watch(self, source, write=True, package=None, run=False, force=False):
        """Watch a source and recompiles on change."""
        from coconut.command.watch import Observer, RecompilationWatcher

        source = fixpath(source)

        logger.show()
        logger.show_tabulated("Watching", showpath(source), "(press Ctrl-C to end)...")

        def recompile(path):
            path = fixpath(path)
            if os.path.isfile(path) and os.path.splitext(path)[1] in code_exts:
                with self.handling_exceptions():
                    if write is True or write is None:
                        writedir = write
                    else:
                        # correct the compilation path based on the relative position of path to source
                        dirpath = os.path.dirname(path)
                        writedir = os.path.join(write, os.path.relpath(dirpath, source))
                    filepaths = self.compile_path(path, writedir, package, run, force, show_unchanged=False)
                    self.run_mypy(filepaths)

        watcher = RecompilationWatcher(recompile)
        observer = Observer()
        observer.schedule(watcher, source, recursive=True)

        with self.running_jobs():
            observer.start()
            try:
                while True:
                    time.sleep(watch_interval)
                    watcher.keep_watching()
            except KeyboardInterrupt:
                logger.show_sig("Got KeyboardInterrupt; stopping watcher.")
            finally:
                observer.stop()
                observer.join()
Watch a source and recompiles on change.