Avoid unnecessary decoding when reading into pandas

Author: pbugnion

docs/source/examples/Widget List.ipynb

@@ -1069,7 +1069,7 @@
     "#=> b'This is the content of example.txt.\\n'\n",
     "```\n",
     "\n",
-    "If the file is a text file, you can get the contents as a string by decoding it:\n",
+    "If the file is a text file, you can get the contents as a string by [decoding it](https://docs.python.org/3/library/codecs.html):\n",
     "\n",
     "```python\n",
     "import codecs\n",
@@ -1084,12 +1084,12 @@
     "    fp.write(uploaded_file[\"content\"])\n",
     "```\n",
     "\n",
-    "To convert the uploaded file into a Pandas dataframe, you need to convert it to a StringIO object:\n",
+    "To convert the uploaded file into a Pandas dataframe, you need to convert it to a [BytesIO object](https://docs.python.org/3/library/io.html#binary-i-o):\n",
     "\n",
     "```python\n",
     "import io\n",
     "import pandas as pd\n",
-    "pd.read_csv(io.StringIO(codecs.decode(uploaded_file[\"content\"], encoding=\"utf-8\")))\n",
+    "pd.read_csv(io.BytesIO(uploaded_file[\"content\"]))\n",
     "```\n",
     "\n",
     "If the uploaded file is an image, you can visualize it with an [image](#Image) widget:\n",