diff --git a/README.md b/README.md
index bab10e5..fce8fde 100644
--- a/README.md
+++ b/README.md
@@ -3143,7 +3143,7 @@ y    2
 | sr.trans(…) |    y  2     |   y     2   |       y  2    |
 +-------------+-------------+-------------+---------------+
 ```
-* **Last result has a hierarchical index. `'<Sr>[<key_1>, <key_2>]'` returns the value.**
+* **Last result has a hierarchical index. Use `'<Sr>[<key_1>, <key_2>]'` to get the value.**
 
 ### DataFrame
 **Table with labeled rows and columns.**
@@ -3387,12 +3387,12 @@ def scrape_data():
     covid = pd.read_csv('https://covid.ourworldindata.org/data/owid-covid-data.csv', 
                         usecols=['date', 'total_cases'])
     covid = covid.groupby('date').sum()
-    dow, gold, bitcoin = [scrape_yahoo(id_) for id_ in ('^DJI', 'GC=F', 'BTC-USD')]
-    dow.name, gold.name, bitcoin.name = 'Dow Jones', 'Gold', 'Bitcoin'
-    return covid, dow, gold, bitcoin
+    dow, gold, btc = [scrape_yahoo(id_) for id_ in ('^DJI', 'GC=F', 'BTC-USD')]
+    dow.name, gold.name, btc.name = 'Dow Jones', 'Gold', 'Bitcoin'
+    return covid, dow, gold, btc
 
-def wrangle_data(covid, dow, gold, bitcoin):
-    df = pandas.concat([covid, dow, gold, bitcoin], axis=1)
+def wrangle_data(covid, dow, gold, btc):
+    df = pandas.concat([covid, dow, gold, btc], axis=1)
     df = df.loc['2020-02-23':].iloc[:-2]
     df = df.interpolate()
     df.iloc[:, 1:] = df.rolling(10, min_periods=1, center=True).mean().iloc[:, 1:]
diff --git a/index.html b/index.html
index 5342577..5f081d8 100644
--- a/index.html
+++ b/index.html
@@ -2681,7 +2681,7 @@ y    <span class="hljs-number">2</span>
 ┗━━━━━━━━━━━━━┷━━━━━━━━━━━━━┷━━━━━━━━━━━━━┷━━━━━━━━━━━━━━━┛
 </code></pre>
 <ul>
-<li><strong>Last result has a hierarchical index. <code class="python hljs"><span class="hljs-string">'&lt;Sr&gt;[&lt;key_1&gt;, &lt;key_2&gt;]'</span></code> returns the value.</strong></li>
+<li><strong>Last result has a hierarchical index. Use <code class="python hljs"><span class="hljs-string">'&lt;Sr&gt;[&lt;key_1&gt;, &lt;key_2&gt;]'</span></code> to get the value.</strong></li>
 </ul>
 <div><h3 id="dataframe">DataFrame</h3><p><strong>Table with labeled rows and columns.</strong></p><pre><code class="python language-python hljs"><span class="hljs-meta">&gt;&gt;&gt; </span>DataFrame([[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>], [<span class="hljs-number">3</span>, <span class="hljs-number">4</span>]], index=[<span class="hljs-string">'a'</span>, <span class="hljs-string">'b'</span>], columns=[<span class="hljs-string">'x'</span>, <span class="hljs-string">'y'</span>])
    x  y
@@ -2871,12 +2871,12 @@ plotly.express.line(df, x=<span class="hljs-string">'Date'</span>, y=<span class
     covid = pd.read_csv(<span class="hljs-string">'https://covid.ourworldindata.org/data/owid-covid-data.csv'</span>, 
                         usecols=[<span class="hljs-string">'date'</span>, <span class="hljs-string">'total_cases'</span>])
     covid = covid.groupby(<span class="hljs-string">'date'</span>).sum()
-    dow, gold, bitcoin = [scrape_yahoo(id_) <span class="hljs-keyword">for</span> id_ <span class="hljs-keyword">in</span> (<span class="hljs-string">'^DJI'</span>, <span class="hljs-string">'GC=F'</span>, <span class="hljs-string">'BTC-USD'</span>)]
-    dow.name, gold.name, bitcoin.name = <span class="hljs-string">'Dow Jones'</span>, <span class="hljs-string">'Gold'</span>, <span class="hljs-string">'Bitcoin'</span>
-    <span class="hljs-keyword">return</span> covid, dow, gold, bitcoin
+    dow, gold, btc = [scrape_yahoo(id_) <span class="hljs-keyword">for</span> id_ <span class="hljs-keyword">in</span> (<span class="hljs-string">'^DJI'</span>, <span class="hljs-string">'GC=F'</span>, <span class="hljs-string">'BTC-USD'</span>)]
+    dow.name, gold.name, btc.name = <span class="hljs-string">'Dow Jones'</span>, <span class="hljs-string">'Gold'</span>, <span class="hljs-string">'Bitcoin'</span>
+    <span class="hljs-keyword">return</span> covid, dow, gold, btc
 
-<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">wrangle_data</span><span class="hljs-params">(covid, dow, gold, bitcoin)</span>:</span>
-    df = pandas.concat([covid, dow, gold, bitcoin], axis=<span class="hljs-number">1</span>)
+<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">wrangle_data</span><span class="hljs-params">(covid, dow, gold, btc)</span>:</span>
+    df = pandas.concat([covid, dow, gold, btc], axis=<span class="hljs-number">1</span>)
     df = df.loc[<span class="hljs-string">'2020-02-23'</span>:].iloc[:<span class="hljs-number">-2</span>]
     df = df.interpolate()
     df.iloc[:, <span class="hljs-number">1</span>:] = df.rolling(<span class="hljs-number">10</span>, min_periods=<span class="hljs-number">1</span>, center=<span class="hljs-keyword">True</span>).mean().iloc[:, <span class="hljs-number">1</span>:]
diff --git a/pdf/index_for_pdf.html b/pdf/index_for_pdf.html
index 0d03f6b..d5b87c9 100644
--- a/pdf/index_for_pdf.html
+++ b/pdf/index_for_pdf.html
@@ -121,7 +121,7 @@
 <strong>regular expressions, <a href="#regex">5</a>-<a href="#specialsequences">6</a></strong><br>
 <strong>requests library, <a href="#scraping">35</a>, <a href="#test">36</a></strong>  </p>
 <h3 id="s">S</h3>
-<p><strong>scraping, <a href="#scraping">35</a>, <a href="#basicmariobrothersexample">43</a>, <a href="#plotly">47</a>, <a href="#confirmedcovidcasesdowjonesgoldandbitcoinprice">48</a></strong><br>
+<p><strong>scraping, <a href="#scraping">35</a>, <a href="#basicmariobrothersexample">43</a>, <a href="#encodedecode">46</a>, <a href="#plotly">47</a>, <a href="#confirmedcovidcasesdowjonesgoldandbitcoinprice">48</a></strong><br>
 <strong>sequence, <a href="#type">4</a>, <a href="#sequence">18</a>, <a href="#abcsequence">19</a></strong><br>
 <strong>sets, <a href="#set">2</a>, <a href="#otheruses">11</a></strong><br>
 <strong>shell commands, <a href="#shellcommands">25</a></strong><br>
diff --git a/pdf/index_for_pdf_print.html b/pdf/index_for_pdf_print.html
index b4169b3..f6d485c 100644
--- a/pdf/index_for_pdf_print.html
+++ b/pdf/index_for_pdf_print.html
@@ -121,7 +121,7 @@
 <strong>regular expressions, 5-6</strong><br>
 <strong>requests library, 35, 36</strong>  </p>
 <h3 id="s">S</h3>
-<p><strong>scraping, 35, 43, 47, 48</strong><br>
+<p><strong>scraping, 35, 43, 46, 47, 48</strong><br>
 <strong>sequence, 4, 18, 19</strong><br>
 <strong>sets, 2, 11</strong><br>
 <strong>shell commands, 25</strong><br>