Requiem.QUIC.NIF.connection_close

You're seeing just the function connection_close, go back to Requiem.QUIC.NIF module for more information.
Link to this function

connection_close(conn, app, err, reason)

Specs

connection_close(integer(), boolean(), non_neg_integer(), binary()) ::
  {:ok, non_neg_integer()} | {:error, :system_error | :already_closed}