diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4db598e..0fd941e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.25)
-project(blt-gp VERSION 0.0.142)
+project(blt-gp VERSION 0.0.143)
 
 include(CTest)
 
diff --git a/include/blt/gp/tree.h b/include/blt/gp/tree.h
index d1293ff..176202e 100644
--- a/include/blt/gp/tree.h
+++ b/include/blt/gp/tree.h
@@ -60,6 +60,13 @@ namespace blt::gp
     {
             using iter_type = std::vector<op_container_t>::const_iterator;
         public:
+            struct child_t
+            {
+                blt::ptrdiff_t start;
+                // one past the end
+                blt::ptrdiff_t end;
+            };
+            
             [[nodiscard]] inline std::vector<op_container_t>& get_operations()
             {
                 return operations;
@@ -117,6 +124,7 @@ namespace blt::gp
             
             bool check(gp_program& program, void* context) const;
             
+            void find_child_extends(gp_program& program, std::vector<child_t>& vec, blt::size_t parent_node, blt::size_t argc) const;
             blt::ptrdiff_t find_endpoint(blt::gp::gp_program& program, blt::ptrdiff_t start) const;
             blt::ptrdiff_t find_parent(blt::gp::gp_program& program, blt::ptrdiff_t start) const;
             
diff --git a/src/tree.cpp b/src/tree.cpp
index d108456..9ec026f 100644
--- a/src/tree.cpp
+++ b/src/tree.cpp
@@ -340,6 +340,26 @@ namespace blt::gp
         }
     }
     
+    void tree_t::find_child_extends(gp_program& program, std::vector<child_t>& vec, blt::size_t parent_node, blt::size_t argc) const
+    {
+        while (vec.size() < argc)
+        {
+            auto current_point = vec.size();
+            child_t prev{};
+            if (current_point == 0)
+            {
+                // first child.
+                prev = {static_cast<blt::ptrdiff_t>(parent_node + 1),
+                        find_endpoint(program, static_cast<blt::ptrdiff_t>(parent_node + 1))};
+                vec.push_back(prev);
+                continue;
+            } else
+                prev = vec[current_point - 1];
+            child_t next = {prev.end, find_endpoint(program, prev.end)};
+            vec.push_back(next);
+        }
+    }
+    
     void population_t::drop(gp_program& program)
     {
         for (auto& pop : get_individuals())