diff --git a/pdf/index_for_pdf.html b/pdf/index_for_pdf.html
index 404221c..7a947d5 100644
--- a/pdf/index_for_pdf.html
+++ b/pdf/index_for_pdf.html
@@ -32,13 +32,13 @@
 <strong>copy function, <a href="#copy">15</a></strong><br>
 <strong>coroutine, <a href="#coroutines">33</a></strong><br>
 <strong>counter, <a href="#counter">2</a>, <a href="#generator">4</a>, <a href="#nonlocal">12</a>, <a href="#iterator-1">17</a></strong><br>
-<strong>csv, <a href="#csv">26</a>, <a href="#printsacsvfileasanasciitable">34</a>, <a href="#encodedecode">46</a></strong><br>
+<strong>csv, <a href="#csv">26</a>, <a href="#printsacsvfileasanasciitable">34</a>, <a href="#encodedecode">46</a>, <a href="#coviddeathsbycontinent">47</a></strong><br>
 <strong>curses module, <a href="#runsaterminalgamewhereyoucontrolanasteriskthatmustavoidnumbers">33</a>, <a href="#curses">34</a></strong><br>
 <strong>cython, <a href="#cython">49</a></strong>  </p>
 <h3 id="d">D</h3>
 <p><strong>dataclasses module, <a href="#namedtupleenumdataclass">12</a>, <a href="#dataclass">15</a></strong><br>
 <strong>datetime module, <a href="#datetime">8</a>-<a href="#constructors">9</a></strong><br>
-<strong>decorator, <a href="#decorator">13</a></strong><br>
+<strong>decorator, <a href="#decorator">13</a>, <a href="#class">14</a>, <a href="#property">15</a>, <a href="#sortable">16</a></strong><br>
 <strong>deques, <a href="#deque">29</a></strong><br>
 <strong>dictionaries, <a href="#dictionary">2</a>, <a href="#abstractbaseclasses">4</a>, <a href="#otheruses">11</a>, <a href="#tableofrequiredandautomaticallyavailablespecialmethods">19</a>, <a href="#collectionsandtheirexceptions">21</a></strong><br>
 <strong>duck types, <a href="#ducktypes">16</a>-<a href="#abcsequence">19</a></strong>  </p>
@@ -62,17 +62,17 @@
 <p><strong>hashable, <a href="#dataclass">15</a>, <a href="#hashable">16</a></strong><br>
 <strong>hexadecimal representation, <a href="#ints">7</a>, <a href="#binhex">8</a>, <a href="#encode-1">28</a></strong>  </p>
 <h3 id="i">I</h3>
-<p><strong>image, <a href="#image">39</a></strong><br>
+<p><strong>image, <a href="#scraping">35</a>, <a href="#image">39</a>-<a href="#animation">40</a>, <a href="#surface">42</a>-<a href="#basicmariobrothersexample">43</a></strong><br>
 <strong>inline, <a href="#otheruses">11</a>-<a href="#namedtupleenumdataclass">12</a>, <a href="#inline-1">15</a>, <a href="#inline-2">20</a></strong><br>
 <strong>input function, <a href="#input">22</a></strong><br>
 <strong>introspection, <a href="#introspection">31</a></strong><br>
 <strong>ints, <a href="#abstractbaseclasses">4</a>, <a href="#ints">7</a>, <a href="#binhex">8</a>, <a href="#encode-1">28</a></strong><br>
 <strong>is operator, <a href="#comparable">16</a></strong><br>
 <strong>iterable, <a href="#abstractbaseclasses">4</a>, <a href="#iterable">18</a>, <a href="#tableofrequiredandautomaticallyavailablespecialmethods">19</a></strong><br>
-<strong>iterator, <a href="#iterator">3</a>, <a href="#iterator-1">17</a></strong><br>
+<strong>iterator, <a href="#enumerate">3</a>-<a href="#generator">4</a>, <a href="#comprehensions">11</a>, <a href="#iterator-1">17</a></strong><br>
 <strong>itertools module, <a href="#itertools">3</a>, <a href="#combinatorics">8</a></strong>  </p>
 <h3 id="j">J</h3>
-<p><strong>json module, <a href="#json">25</a>, <a href="#encodedecode">46</a></strong>  </p>
+<p><strong>json, <a href="#json">25</a>, <a href="#restrequest">36</a>, <a href="#encodedecode">46</a></strong>  </p>
 <h3 id="l">L</h3>
 <p><strong>lambda, <a href="#lambda">11</a></strong><br>
 <strong>list comprehension, <a href="#comprehensions">11</a></strong><br>
@@ -126,9 +126,9 @@
 <strong>slots attribute, <a href="#slots">15</a></strong><br>
 <strong>sortable, <a href="#list">1</a>, <a href="#sortable">16</a></strong><br>
 <strong>splat operator, <a href="#splatoperator">10</a>-<a href="#otheruses">11</a></strong><br>
-<strong>sqlite module, <a href="#sqlite">27</a></strong><br>
-<strong>statistics, <a href="#statistics">7</a>, <a href="#numpy">37</a>-<a href="#indexing">38</a></strong>, <a href="#pandas">44</a>-<a href="#confirmedcovidcasesdowjonesgoldandbitcoinprice">48</a><br>
-<strong>strings, <a href="#string">5</a></strong><br>
+<strong>sql, <a href="#sqlite">27</a>, <a href="#encodedecode">46</a></strong><br>
+<strong>statistics, <a href="#statistics">7</a>, <a href="#numpy">37</a>-<a href="#indexing">38</a>, <a href="#pandas">44</a>-<a href="#confirmedcovidcasesdowjonesgoldandbitcoinprice">48</a></strong><br>
+<strong>strings, <a href="#abstractbaseclasses">4</a>-<a href="#comparisonofpresentationtypes">7</a>, <a href="#class">14</a></strong><br>
 <strong>struct module, <a href="#struct">28</a>-<a href="#integertypesuseacapitalletterforunsignedtypeminimumandstandardsizesareinbrackets">29</a></strong><br>
 <strong>subprocess module, <a href="#sends11tothebasiccalculatorandcapturesitsoutput">25</a></strong><br>
 <strong>super function, <a href="#inheritance">14</a></strong><br>
@@ -140,7 +140,7 @@
 <strong>threading module, <a href="#threading">30</a></strong><br>
 <strong>time module, <a href="#progressbar">34</a>, <a href="#stopwatch">36</a></strong><br>
 <strong>tuples, <a href="#tuple">3</a>, <a href="#abstractbaseclasses">4</a>, <a href="#otheruses">11</a></strong><br>
-<strong>type, <a href="#type">4</a>, <a href="#type-1">31</a></strong>  </p>
+<strong>type, <a href="#type">4</a>, <a href="#metaprograming">31</a>-<a href="#metaclass">32</a></strong>  </p>
 <h3 id="w">W</h3>
 <p><strong>wave module, <a href="#audio">40</a>-<a href="#writefloatsamplestowavfile">41</a></strong><br>
 <strong>web, <a href="#web">36</a></strong>  </p> 
diff --git a/pdf/index_for_pdf_print.html b/pdf/index_for_pdf_print.html
index 2fb7dcc..21c4553 100644
--- a/pdf/index_for_pdf_print.html
+++ b/pdf/index_for_pdf_print.html
@@ -32,13 +32,13 @@
 <strong>copy function, 15</strong><br>
 <strong>coroutine, 33</strong><br>
 <strong>counter, 2, 4, 12, 17</strong><br>
-<strong>csv, 26, 34, 46</strong><br>
+<strong>csv, 26, 34, 46, 47</strong><br>
 <strong>curses module, 33, 34</strong><br>
 <strong>cython, 49</strong>  </p>
 <h3 id="d">D</h3>
 <p><strong>dataclasses module, 12, 15</strong><br>
 <strong>datetime module, 8-9</strong><br>
-<strong>decorator, 13</strong><br>
+<strong>decorator, 13, 14, 15, 16</strong><br>
 <strong>deques, 29</strong><br>
 <strong>dictionaries, 2, 4, 11, 19, 21</strong><br>
 <strong>duck types, 16-19</strong>  </p>
@@ -62,17 +62,17 @@
 <p><strong>hashable, 15, 16</strong><br>
 <strong>hexadecimal representation, 7, 8, 28</strong>  </p>
 <h3 id="i">I</h3>
-<p><strong>image, 39</strong><br>
+<p><strong>image, 25, 39-40, 42-43</strong><br>
 <strong>inline, 11-12, 15, 20</strong><br>
 <strong>input function, 22</strong><br>
 <strong>introspection, 31</strong><br>
 <strong>ints, 4, 7, 8, 28</strong><br>
 <strong>is operator, 16</strong><br>
 <strong>iterable, 4, 18, 19</strong><br>
-<strong>iterator, 3, 17</strong><br>
+<strong>iterator, 3-4, 11, 17</strong><br>
 <strong>itertools module, 3, 8</strong>  </p>
 <h3 id="j">J</h3>
-<p><strong>json module, 25, 46</strong>  </p>
+<p><strong>json, 25, 36, 46</strong>  </p>
 <h3 id="l">L</h3>
 <p><strong>lambda, 11</strong><br>
 <strong>list comprehension, 11</strong><br>
@@ -86,7 +86,7 @@
 <strong>memoryviews, 29</strong><br>
 <strong>metaclass attribute, 32</strong><br>
 <strong>metaprograming, 31-32</strong><br>
-<strong>mysql library, 26</strong>  </p>
+<strong>mysql library, 27</strong>  </p>
 <h3 id="n">N</h3>
 <p><strong>namedtuples, 3</strong><br>
 <strong>nonlocal keyword, 12</strong><br>
@@ -126,9 +126,9 @@
 <strong>slots attribute, 15</strong><br>
 <strong>sortable, 1, 16</strong><br>
 <strong>splat operator, 10-11</strong><br>
-<strong>sqlite module, 27, 46</strong><br>
+<strong>sql, 27, 46</strong><br>
 <strong>statistics, 7, 37-38, 44-48</strong><br>
-<strong>strings, 5</strong><br>
+<strong>strings, 4-7, 14</strong><br>
 <strong>struct module, 28-29</strong><br>
 <strong>subprocess module, 25</strong><br>
 <strong>super function, 14</strong><br>