Send a frame just after the connected

[alvises]

defmodule GdaxStream.Client do
  use WebSockex

  def start_link(url, state) do
    WebSockex.start_link(url, __MODULE__, state)
  end

  def handle_connect(conn, state) do
    IO.puts("connected!")
    {:ok, state}
  end

end

What can I do if I want to send a subscription frame just after connected?

  def subscription_frame() do
    data =
      Poison.encode!(%{
        type: "subscribe",
        product_ids: ["BTC-USD"],
        channels: ["ticker"]
      })

    {:text, data}
  end

  def handle_connect(conn, state) do
    WebSockex.send_frame(self(), subscription_frame())
    {:ok, state}
  end

doing so doesn't work, {:error, %WebSockex.CallingSelfError{function: :send_frame}}

[alvises]

Actually, I've just seen, in one of your examples, solution that works in my case (https://github.com/Azolo/websockex/blob/master/examples/chrome_debbuger.exs)

  def start_link(products \\ [], options \\ []) do
    {:ok, pid} = WebSockex.start_link(@url, __MODULE__, %{}, options) do
    subscribe(pid, products)
    {:ok, pid}
  end