I am new on kotlin android. I have created the adapter for recyclerview. But I am not able to perform a click event for each recyclerview item. I need the explanation with the reference code. 
Kindly help me to do this.
Thanks in advance.
Here is my code for your reference.

```
  class CustomAdapter(val readerList: ReaderResponse, mainActivity: 
    MainActivity,val btnlistener: BtnClickListener) : 
    RecyclerView.Adapter<CustomAdapter.ViewHolder>() {

    companion object {
        var mClickListener: BtnClickListener? = null
    }

    override fun onCreateViewHolder(viewgroup: ViewGroup, index: Int): ViewHolder 
    {

        val view=LayoutInflater.from(viewgroup?.context).inflate(R.layout.reader_list,viewgroup,false)
        return ViewHolder(view)
    }

    override fun getItemCount(): Int {
        return readerList.results.size

    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {

        mClickListener = btnlistener
        val item = readerList

        val reader:ReaderData = readerList.results[position]
        /*p0?.imageview?.text=reader.readerIcon*/
        holder?.reader_status?.text=reader.readerStatus
        holder?.ward_name?.text=reader.wardName
        holder?.reader_id?.text=reader.readerID
        holder?.reader_name?.text=reader.readerName
        holder?.reader_location?.text=reader.readerLocation

        if (reader.readerStatus.toLowerCase().equals("yes")){
            holder.reader_name.setTextColor(Color.parseColor("#24a314"))
        }else if (reader.readerStatus.toLowerCase().equals("no")){

            holder.reader_name.setTextColor(Color.parseColor("#f4312d"))
            holder.warning.setVisibility(View.VISIBLE)
        }
    }

    class ViewHolder(itemView: View) :RecyclerView.ViewHolder(itemView) {

        val imageview = itemView.findViewById(R.id.imageview) as Button
        val reader_name = itemView.findViewById(R.id.reader_name) as TextView
        val reader_location = itemView.findViewById(R.id.floor_no) as TextView
        val ward_name = itemView.findViewById(R.id.ward_name) as TextView
        val reader_id = itemView.findViewById(R.id.reader_id) as TextView
        val reader_status = itemView.findViewById(R.id.reader_status) as TextView
        val warning=itemView.findViewById(R.id.warning) as Button

      }
      open interface BtnClickListener {
        fun onBtnClick(position: Int)
     }

     }

```