Update Pygments example to not fail when the lang is unknown.

docs/index.rst

@@ -66,19 +66,22 @@ used to escape the HTML):
  import houdini as h
  import misaka as m
  from pygments import highlight
- from pygments.formatters import HtmlFormatter
+ from pygments.formatters import HtmlFormatter, ClassNotFound
  from pygments.lexers import get_lexer_by_name
 
  class HighlighterRenderer(m.HtmlRenderer):
  def blockcode(self, text, lang):
- if not lang:
- return '\n<pre><code>{}</code></pre>\n'.format(
- h.escape_html(text.strip()))
-
- lexer = get_lexer_by_name(lang, stripall=True)
- formatter = HtmlFormatter()
-
- return highlight(text, lexer, formatter)
+ try:
+ lexer = get_lexer_by_name(lang, stripall=True)
+ except ClassNotFound:
+ lexer = None
+
+ if lexer:
+ formatter = HtmlFormatter()
+ return highlight(text, lexer, formatter)
+ # default
+ return '\n<pre><code>{}</code></pre>\n'.format(
+ h.escape_html(text.strip()))
 
  renderer = HighlighterRenderer()
  md = m.Markdown(renderer, extensions=('fenced-code',))