diff --git a/src/collections/scoped_buffer.rs b/src/collections/scoped_buffer.rs
index 7f5194cf31bc6ef317490d82f6dc413fb07e2272..518c889433f8045e9c80d5ce3862414e60c38369 100644
--- a/src/collections/scoped_buffer.rs
+++ b/src/collections/scoped_buffer.rs
@@ -73,54 +73,80 @@ pub(crate) struct ScopedSection<T: Sized> {
 }
 
 impl<T: Sized> ScopedSection<T> {
+    /// Pushes value into section
     #[inline]
     pub(crate) fn push(&mut self, value: T) {
+        self.check_length();
         let vec = unsafe{&mut *self.inner};
-        hide!(debug_assert_eq!(
-            vec.len(), self.cur_size as usize,
-            "trying to push onto section, but size is larger than expected"
-        ));
         vec.push(value);
         hide!(self.cur_size += 1);
     }
 
     #[inline]
     pub(crate) fn len(&self) -> usize {
+        self.check_length();
         let vec = unsafe{&mut *self.inner};
-        hide!(debug_assert_eq!(
-            vec.len(), self.cur_size as usize,
-            "trying to get section length, but size is larger than expected"
-        ));
         return vec.len() - self.start_size as usize;
     }
 
     #[inline]
     #[allow(unused_mut)] // used in debug mode
     pub(crate) fn forget(mut self) {
+        self.check_length();
         let vec = unsafe{&mut *self.inner};
-        hide!({
-            debug_assert_eq!(
-                vec.len(), self.cur_size as usize,
-                "trying to forget section, but size is larger than expected"
-            );
-            self.cur_size = self.start_size;
-        });
+        hide!(self.cur_size = self.start_size);
         vec.truncate(self.start_size as usize);
     }
 
     #[inline]
     #[allow(unused_mut)] // used in debug mode
     pub(crate) fn into_vec(mut self) -> Vec<T> {
+        self.check_length();
         let vec = unsafe{&mut *self.inner};
+        hide!(self.cur_size = self.start_size);
+        let section = Vec::from_iter(vec.drain(self.start_size as usize..));
+        section
+    }
+
+    #[inline]
+    pub(crate) fn check_length(&self) {
         hide!({
+            let vec = unsafe{&*self.inner};
             debug_assert_eq!(
                 vec.len(), self.cur_size as usize,
-                "trying to turn section into vec, but size is larger than expected"
-            );
-            self.cur_size = self.start_size;
-        });
-        let section = Vec::from_iter(vec.drain(self.start_size as usize..));
-        section
+                "incorrect use of ScopedSection: underlying storage vector has changed size"
+            )
+        })
+    }
+}
+
+impl<T: Sized + PartialEq> ScopedSection<T> {
+    #[inline]
+    pub(crate) fn push_unique(&mut self, value: T) {
+        self.check_length();
+        let vec = unsafe{&mut *self.inner};
+        for item in &vec[self.start_size as usize..] {
+            if *item == value {
+                // item already exists
+                return;
+            }
+        }
+
+        vec.push(value);
+        hide!(self.cur_size += 1);
+    }
+
+    #[inline]
+    pub(crate) fn contains(&self, value: &T) -> bool {
+        self.check_length();
+        let vec = unsafe{&*self.inner};
+        for index in self.start_size..vec.len() {
+            if vec[index] == value {
+                return true;
+            }
+        }
+
+        return false;
     }
 }