Remove a function from xformatter

examples/user_guide/Customizing_Plots.ipynb

@@ -650,7 +650,6 @@
     "Tick formatting works very differently in different backends, however the ``xformatter`` and ``yformatter`` options try to minimize these differences. Tick formatters may be defined in one of three formats:\n",
     "\n",
     "* A classic format string such as ``'%d'``, ``'%.3f'`` or ``'%d'`` which may also contain other characters (``'$%.2f'``)\n",
-    "* A function which will be compiled to JS using pscript (if installed) when using bokeh\n",
     "* A ``bokeh.models.TickFormatter`` in bokeh and a ``matplotlib.ticker.Formatter`` instance in matplotlib\n",
     "\n",
     "Here is a small example demonstrating how to use the string format and function approaches:"
@@ -662,10 +661,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "def formatter(value):\n",
-    "    return str(value) + ' days'\n",
-    "\n",
-    "curve.relabel('Tick formatters').opts(xformatter=formatter, yformatter='$%.2f', width=500)"
+    "curve.relabel('Tick formatters').opts(xformatter='%.0f days', yformatter='$%.2f', width=500)"
    ]
   },
   {