How to create Text Watcher in Android kotlin ?

var etsearch: EditText? = null

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    etsearch!!.addTextChangedListener(object : TextWatcher {
        override fun afterTextChanged(s: Editable?) {

        }

        override fun beforeTextChanged(s: CharSequence?, 

                   start: Int, count: Int, after: Int) {

        }

        override fun onTextChanged(s: CharSequence?, 

                  start: Int, before: Int, count: Int) {

        }
    })
}