fn read(
next_line: Option<&[u8]>,
section: &mut Option<SectionLabel>,
b64buf: &mut Vec<u8>,
) -> Result<ControlFlow<Option<(SectionKind, Vec<u8>)>, ()>, Error>fn read(
next_line: Option<&[u8]>,
section: &mut Option<SectionLabel>,
b64buf: &mut Vec<u8>,
) -> Result<ControlFlow<Option<(SectionKind, Vec<u8>)>, ()>, Error>