Delete redundant summation function

Author: zzhengnan

06_distributed_advanced.ipynb

@@ -540,13 +540,9 @@
     "def ratio(a, b):\n",
     "    return a // b\n",
     "\n",
-    "@delayed\n",
-    "def summation(*a):\n",
-    "    return sum(a)\n",
-    "\n",
     "ina = [5, 25, 30]\n",
     "inb = [5, 5, 6]\n",
-    "out = summation(*[ratio(a, b) for (a, b) in zip(ina, inb)])\n",
+    "out = delayed(sum)([ratio(a, b) for (a, b) in zip(ina, inb)])\n",
     "f = c.compute(out)\n",
     "f"
    ]
@@ -571,7 +567,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "But if we introduce bad input, an exception is raised. The exception happens in `ratio`, but only comes to our attention when calculating `summation`."
+    "But if we introduce bad input, an exception is raised. The exception happens in `ratio`, but only comes to our attention when calculating the sum."
    ]
   },
   {
@@ -586,7 +582,7 @@
    "source": [
     "ina = [5, 25, 30]\n",
     "inb = [5, 0, 6]\n",
-    "out = summation(*[ratio(a, b) for (a, b) in zip(ina, inb)])\n",
+    "out = delayed(sum)([ratio(a, b) for (a, b) in zip(ina, inb)])\n",
     "f = c.compute(out)\n",
     "c.gather(f)"
    ]