5.3.8.3 expr="..." attribute

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5.3.8.3 `expr="..."` attribute

The `expr` attribute specifies an expression that yields a sequence that the iterator specified in the `iter` (5.3.8.5) attribute will iterate over. All of the enclosed content is then evaluated for each element in the sequence.

For example:

    >>> import albatross
    >>> ctx = albatross.SimpleContext('.')
    >>> albatross.Template(ctx, '<magic>', '''
    ... <al-for iter="i" expr="range(15)" whitespace="indent">
    ...  <al-value expr="i.value()">
    ... </al-for whitespace>
    ... ''').to_html(ctx)
    >>> ctx.flush_content()
     0 1 2 3 4 5 6 7 8 9 10 11 12 13 14