/// <summary>
/// Peeks at the next field tag. This is like calling <see cref="ReadTag"/>, but the
/// tag is not consumed. (So a subsequent call to <see cref="ReadTag"/> will return the
/// same value.)
/// </summary>
public uint PeekTag()
{
var span = new ReadOnlySpan <byte>(buffer);
return(ParsingPrimitives.PeekTag(ref span, ref state));
}