>>> import albatross
>>> class Ctx(albatross.SimpleContext):
...     def input_add(self, *args):
...         print args
... 
>>> ctx = Ctx('.')
>>> ctx.locals.swallows = ['African', 'European']
>>> ctx.locals.num = 0
>>> albatross.Template(ctx, '<magic>', '''
... <al-input type="radio" name="swallow" expr="swallows[num]" value="African" whitespace>
... <al-input type="radio" name="swallow" expr="swallows[num]" value="European" whitespace>
... ''').to_html(ctx)
('radio', 'swallow', 'African', False)
('radio', 'swallow', 'European', False)
>>> ctx.flush_content()
<input type="radio" name="swallow" value="African" checked />
<input type="radio" name="swallow" value="European" />
