Kotlin: editText Observable extension in Android

EditTextUtils.kt

fun EditText.toObservable(): Observable<String> {
    return Observable.create({
        val watcher = object : TextWatcher {

            override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
                scream("aaa" + p0.toString())
                it.onNext(p0.toString())
            }

            override fun afterTextChanged(p0: Editable?) { }

            override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) { }
        }
        this.addTextChangedListener(watcher)
        it.setCancellable { this.removeTextChangedListener(watcher) }
    })
}