Merge pull request #40 from polonez/master

Fix typo: remove duplicate 'to'

ipynb/TSP.ipynb

@@ -1459,7 +1459,7 @@
    "metadata": {},
    "source": [
     "Note: Each time we develop a new algorithm, we would like to compare its performance to some standard old algorithms.\n",
-    "The use of `@functools.lru_cache` here means that we don't need to to re-run the old algorithms on a standard data set each time; we can just cache the old results. \n",
+    "The use of `@functools.lru_cache` here means that we don't need to re-run the old algorithms on a standard data set each time; we can just cache the old results. \n",
     "\n",
     "We can use `benchmark` to see the average call to the absolute value function takes less than a microsecond:"
    ]