diff --git a/img/12-0.jpg b/img/12-0.jpg
new file mode 100644
index 0000000..b90572f
Binary files /dev/null and b/img/12-0.jpg differ
diff --git a/img/12-1.svg b/img/12-1.svg
new file mode 100644
index 0000000..3aab520
--- /dev/null
+++ b/img/12-1.svg
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="169" height="240" viewBox="-7 -10 169 240"><style>
+    @font-face {
+      font-family: 'PT Mono';
+      font-style: normal;
+      font-weight: 400;
+      src: local('PT Mono'), local('PTMono-Regular'), url(http://themes.googleusercontent.com/static/fonts/ptmono/v1/jmle3kzCPnW8O7_gZGRDlQ.woff) format('woff');
+    }
+    .ast-text { font-family: "PT Mono"; font-size: 14px; stroke: none; }
+  </style>
+<g><ellipse cx="0" cy="0" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="13" y="4.5" class="ast-text">do</text><ellipse cx="30" cy="20" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="43" y="24.5" class="ast-text">define</text><path d="M 0.5 5.5 L 0.5 10.5 A 10 10 0 0 0 10.5 20.5 L 25.5 20.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(25.5 20.5) rotate(90) scale(1)"></path><ellipse cx="60" cy="40" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="73" y="44.5" class="ast-text">x</text><path d="M 30.5 25.5 L 30.5 30.5 A 10 10 0 0 0 40.5 40.5 L 55.5 40.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(55.5 40.5) rotate(90) scale(1)"></path><ellipse cx="60" cy="60" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="73" y="64.5" class="ast-text">10</text><path d="M 30.5 25.5 L 30.5 50.5 A 10 10 0 0 0 40.5 60.5 L 55.5 60.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(55.5 60.5) rotate(90) scale(1)"></path><ellipse cx="30" cy="80" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="43" y="84.5" class="ast-text">if</text><path d="M 0.5 5.5 L 0.5 70.5 A 10 10 0 0 0 10.5 80.5 L 25.5 80.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(25.5 80.5) rotate(90) scale(1)"></path><ellipse cx="60" cy="100" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="73" y="104.5" class="ast-text">&gt;</text><path d="M 30.5 85.5 L 30.5 90.5 A 10 10 0 0 0 40.5 100.5 L 55.5 100.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(55.5 100.5) rotate(90) scale(1)"></path><ellipse cx="90" cy="120" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="103" y="124.5" class="ast-text">x</text><path d="M 60.5 105.5 L 60.5 110.5 A 10 10 0 0 0 70.5 120.5 L 85.5 120.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(85.5 120.5) rotate(90) scale(1)"></path><ellipse cx="90" cy="140" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="103" y="144.5" class="ast-text">5</text><path d="M 60.5 105.5 L 60.5 130.5 A 10 10 0 0 0 70.5 140.5 L 85.5 140.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(85.5 140.5) rotate(90) scale(1)"></path><ellipse cx="60" cy="160" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="73" y="164.5" class="ast-text">print</text><path d="M 30.5 85.5 L 30.5 150.5 A 10 10 0 0 0 40.5 160.5 L 55.5 160.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(55.5 160.5) rotate(90) scale(1)"></path><ellipse cx="90" cy="180" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="103" y="184.5" class="ast-text">"large"</text><path d="M 60.5 165.5 L 60.5 170.5 A 10 10 0 0 0 70.5 180.5 L 85.5 180.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(85.5 180.5) rotate(90) scale(1)"></path><ellipse cx="60" cy="200" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="73" y="204.5" class="ast-text">print</text><path d="M 30.5 85.5 L 30.5 190.5 A 10 10 0 0 0 40.5 200.5 L 55.5 200.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(55.5 200.5) rotate(90) scale(1)"></path><ellipse cx="90" cy="220" rx="5" ry="5" fill="black" width="10" height="10"></ellipse><text x="103" y="224.5" class="ast-text">"small"</text><path d="M 60.5 205.5 L 60.5 210.5 A 10 10 0 0 0 70.5 220.5 L 85.5 220.5" stroke="black" fill="none"></path><path d="M 0 0 L 3 8 L 0 7 L -3 8 Z" stroke="none" fill="rgb(0, 0, 0)" transform="translate(85.5 220.5) rotate(90) scale(1)"></path></g></svg>
\ No newline at end of file