If you paste a very very long code into mediawiki, you may find that code takes too much space that it is not easy to find the useful content. Why not add a new template that can fold up the code?
add two tags: {{hideBegin}}, {{hideEnd}}, your wiki code looks like this
{{hideBegin}}
Long Code
Long Code
Long Code
{{hideEnd}},
then preview the page, and edit that two new template:
for hideBegin:
<div style='border:0px;padding:3px; PADDING:0px; width:100%; height:480px; LINE-HEIGHT: 20px; OVERFLOW: auto;'><div class="NavContent" style="{{{ContentStyle|}}}"><noinclude></div></div>
{{Documentation}}
[[en:Template:hideBegin]]
[[ja:Template:hideBegin]]
</noinclude>
for hideEnd:
</div></div><noinclude>{{Documentation}}</noinclude>
That's all.
WikiMedia template mechanism is really COOL!