Function read 

pub fn read<'a>(
    parent: &ScopedReader<'a, '_>,
    element: &Element<'a>,
    field: &'static str,
) -> Result<AlgorithmIdentifier<'a>>

Reads an algorithm identifier from an element a schema said is one.

It is public because certificates are not the only place this structure appears: a signed message names a digest and a signature algorithm the same way, and reading them a second time somewhere else would be a second set of rules about what parameters are allowed to look like.

Errors

Reports the encoding fault and the field it was in.