To add variable initialization for nu18 to pass Travis

kakirastern · web-flow · commit e7876665d781 · 2019-02-13T00:36:48.000+08:00
Completing pair-wise definition of `nu13` and `nu18`.
diff --git a/tutorials/notebooks/quantities/quantities.ipynb b/tutorials/notebooks/quantities/quantities.ipynb
@@ -634,7 +634,8 @@
    },
    "outputs": [],
    "source": [
-    "nu13 = lambda13.to(u.Hz)"
+    "nu13 = lambda13.to(u.Hz)\n",
+    "nu18 = lambda13.to(u.Hz)"
    ]
   },
   {
