Why doesn't gulp.watch finish on gulp 4?

Question

Sass

Good afternoon.
I was setting up my gulp (1 time) and ran into a problem. when writing a watcher, it does not give an error, but it does not work correctly either.
when I write gulp watch it starts but does not finish. What could be the problem?
Here is the code I have

var gulp = require('gulp'),
sass = require('gulp-sass');
/* task for sass from sass folder */
gulp.task('sass', function () {
return gulp.src('app/sass/**/*.sass')
.pipe(sass())
.pipe( gulp.dest('app/css'))
});
gulp.task('watch', function () {
gulp.watch('app/sass/**/*.sass', gulp.parallel['sass']);
});

Answer 1

So he shouldn't finish. You gave him a command to observe and initiate any actions in case of changes.