>>> import albatross
>>> ctx = albatross.SimpleContext('.')
>>> albatross.Template(ctx, '<magic>', '''
... <al-macro name="yummy">
...  <al-for iter="i" expr="range(3)">
...   <al-usearg whitespace="indent">
...  </al-for>
... </al-macro>
... ''').to_html(ctx)
>>> ctx.locals.food = 'spam'
>>> albatross.Template(ctx, '<magic>', '''
... <al-expand name="yummy">
...  <al-exec expr="food = food + '!'">
...  <al-value expr="food">
... </al-expand whitespace>
... ''').to_html(ctx)
>>> ctx.flush_content()
spam! spam!! spam!!!