    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/system-design-primer-primer)."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
 
</s>
    "This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/system-design-primer)."
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
    "This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/system-design-primer)."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
keep keep keep keep replace keep keep keep keep keep
 Resolve #195: Fix broken GitHub URLs (#199)
solutions/object_oriented_design/online_chat/online_chat.ipynb