Function compile_scopes 

pub fn compile_scopes<'a, I>(scopes: I) -> Option<Expr>
where
    I: IntoIterator<Item = (&'a str, &'a str)>,

Builds the expression equivalent to a set of legacy (scope_type, scope_value) rows, which always meant “any of these matches”.

Returns None when there are no rows — the caller must treat that as “no grant”, not “no restriction”.