Make StepCursor::advance private
diff --git a/src/group.rs b/src/group.rs
index 9eb005e..b2e4659 100644
--- a/src/group.rs
+++ b/src/group.rs
@@ -75,7 +75,8 @@
     input.step(|cursor| {
         if let Some((content, span, rest)) = cursor.group(delimiter) {
             let unexpected = private::get_unexpected(input);
-            let content = private::new_parse_buffer(span, cursor.advance(content), unexpected);
+            let nested = private::advance_step_cursor(cursor, content);
+            let content = private::new_parse_buffer(span, nested, unexpected);
             Ok(((span, content), rest))
         } else {
             let message = match delimiter {