diff --git a/src/virtual_memory.rs b/src/virtual_memory.rs
index 392e76e..bbcad86 100644
--- a/src/virtual_memory.rs
+++ b/src/virtual_memory.rs
@@ -22,6 +22,11 @@ pub unsafe trait Reservation: Sized + Ord + Drop {
     unsafe fn commitPages(&mut self, indexOfFirst: usize, count: usize) -> *mut [u8];
     unsafe fn decommitPages(&mut self, indexOfFirst: usize, count: usize);
     unsafe fn release(self);
+
+    fn isFollowedBy(&self, next: &Self) -> bool;
+    fn isPrecededBy(&self, next: &Self) -> bool {
+        return next.isFollowedBy(self);
+    }
 }
 
 pub enum ExtendResult<T> {