pub fn token_reader<'q, 'a: 'q>(
attribute: &Attribute<'a>,
parent: &Reader<'q>,
) -> Result<Reader<'q>>Expand description
A reader over the one time-stamp token of an archive-time-stamp-v3
attribute, for Token::read_from.
EN 319 122-1 §5.5.3 gives the attribute exactly one AttributeValue.
§Errors
An attribute of another type, a value count other than one, a foreign reader, or a spent work ceiling.