How to get the child elements of IQ using ejabberd hook muc_process_iq

I am creating a custom module for ejabberd using elixir , I am able to filter the IQ using ejabberd hook :muc_process_iq but I don't know how to get different child elements and values from that IQ.

defmodule FilterPacket do
  require Logger
  @behaviour :gen_mod

  def start(host, _opts) do
    Logger.info('Starting ejabberd module Filter Packet')
    Ejabberd.Hooks.add(:muc_process_iq, host, __MODULE__, :on_filter_packet, 50)
    :ok
  end

  def stop(host) do
    Logger.info('Stopping ejabberd module Filter Packet')
    Ejabberd.Hooks.delete(:muc_process_iq, host, __MODULE__, :on_filter_packet, 50)
    :ok
  end

  def on_filter_packet(iq, state) do
    Logger.info("This is IQ #{inspect iq}")
    # I want to get the child elements of the IQ here 
  end

  def depends(_host, _opts) do
    []
  end

  def mod_options(_host) do
    []
  end
end