{"ast_node_type":"function","tokens":[{"end":91,"kind":"keyword","start":0,"text":"fn"}]}
    fn expand_or_pat(&self, parent_row: usize) -> impl Iterator<Item = MatrixRow<'p, Cx>> {
    // Expand the first or-pattern (if any) into its subpatterns. Panics if `self` is empty.
        let is_or_pat = self.pats.head().is_or_pat();