>>> import albatross
>>> ctx = albatross.SimpleContext('.')
>>> albatross.Template(ctx, '<magic>', '''
... <al-macro name="oops">
...  <al-value expr="oops">
... </al-macro>
... ''').to_html(ctx)
>>> ctx.flush_content()
>>> templ = albatross.Template(ctx, '<magic>', '''
... <al-expand name="oops"/>
... ''')
>>> try:
...     templ.to_html(ctx)
...     ctx.flush_content()
... except NameError, e:
...     print e
... 
name 'oops' is not defined
>>> ctx.locals.oops = 'there is now'
>>> templ.to_html(ctx)
>>> ctx.flush_content()
there is now