ulong -a eq (p_retail_product item_1, p_retail_product item_2)
{
  ...
}

ulong -a eq (p_retail_product item_1, p_ws_product item_2)
{
  ...
}

ulong -a eq (p_ws_product item_1, p_retail_product item_2)
{
  ...
}

ulong -a eq (p_ws_product item_1, p_ws_product item_2)
{
  ...
}
