Remove common indentation of code blocks.

scripts/generate.py

@@ -288,7 +288,20 @@ def render_list_item(element, acc):
 
 def render_code_block(element, acc):
     acc.append('<pre><code>')
-    acc.append(html.escape(element.lines))
+    content = html.escape(element.lines)
+
+    # Remove indentation common to all lines
+    base_indentation = min([
+        len(l) - len(l.lstrip(' '))
+        for l in content.split('\n')
+        if len(l.strip()) > 0
+    ])
+    content_lines = [
+        l[base_indentation:]
+        for l in content.split('\n')
+    ]
+
+    acc.append('\n'.join(content_lines))
     acc.append('</code></pre>')
 
 def render_results_block(element, acc):