diff --git a/ngcp/utils.lua b/ngcp/utils.lua
index ac7fe43..1333e2c 100644
--- a/ngcp/utils.lua
+++ b/ngcp/utils.lua
@@ -159,12 +159,26 @@ end
 
 -- GLOBAL
 Stack = {
-  __class__ = 'Stack',
+  __class__ = 'Stack'
 }
 Stack_MT = {
-  __index = Stack,
   __tostring = function(t)
     return table.tostring(Stack.list(t))
+  end,
+  -- this works only on Lua5.2
+  __len = function(t)
+    return Stack.size(t)
+  end,
+  __index = function(t,k)
+    if type(k) == 'number' then
+      return Stack.get(t,k)
+    end
+    return rawget(Stack,k)
+  end,
+  __newindex = function(t,k,v)
+    if type(k) == 'number' then
+      Stack.set(t,k,v)
+    end
   end
 }
 
@@ -174,6 +188,7 @@ Stack_MT = {
     setmetatable(t, Stack_MT)
     return t
   end
+
   -- push a value on to the stack
   function Stack:push(...)
     if ... then
@@ -208,6 +223,30 @@ Stack_MT = {
     return unpack(entries)
   end
 
+  -- get pos ( starts on 0)
+  function Stack:get(pos)
+    assert(pos)
+    assert(pos>=0)
+    local indx = #self._et - pos
+    if indx>0 then
+      return self._et[indx]
+    end
+  end
+
+  -- set a value in a pos (stars on 0)
+  function Stack:set(pos, value)
+    assert(pos)
+    assert(pos>=0)
+    local indx = #self._et - pos
+    if indx>0 then
+      if self._et[indx] then
+        self._et[indx] = value
+      else
+        error("No pos:"..pos)
+      end
+    end
+  end
+
   -- get entries
   function Stack:size()
     return #self._et
diff --git a/tests/utils.lua b/tests/utils.lua
index 5029968..98cd463 100644
--- a/tests/utils.lua
+++ b/tests/utils.lua
@@ -103,23 +103,117 @@ TestUtils = {} --class
 
 TestStack = {}
     function TestStack:test()
-        s = Stack:new()
-        assertEquals(#s._et,0)
+        local s = Stack:new()
+        assertEquals(type(s), 'table')
+        assertEquals(s.__class__, 'Stack')
+    end
+
+    function TestStack:test_size()
+        local s = Stack:new()
+        assertEquals(s:size(),0)
+        s:push(1)
+        assertEquals(s:size(),1)
+        s:pop()
+        assertEquals(s:size(),0)
+    end
+
+    function TestStack:test_push()
+        local s s = Stack:new()
+        s:push(1)
+        assertEquals(s:size(),1)
+    end
+
+    function TestStack:test_pop()
+        local s = Stack:new()
         assertEquals(s:pop(), nil)
         s:push(1)
-        assertEquals(#s._et,1)
+        assertEquals(s:size(),1)
         assertEquals(s:pop(),1)
         assertEquals(s:size(),0)
+    end
+
+    function TestStack:test_get()
+        local s = Stack:new()
         s:push(1)
+        assertEquals(s:get(0),1)
         s:push({1,2,3})
+        assertEquals(s:get(0),{1,2,3})
+        assertEquals(s:get(1),1)
+        assertError(s.get, s, -1)
+        assertIsNil(s:get(2))
+    end
+
+    function TestStack:test_get_op()
+        local s = Stack:new()
+        s:push(1)
+        assertEquals(s[0],1)
+        s:push({1,2,3})
+        assertEquals(s[0],{1,2,3})
+        assertEquals(s[1],1)
+        assertIsNil(s[2])
+    end
+
+    function TestStack:test_set()
+        local s = Stack:new()
+        s:push(1)
+        s:push({1,2,3})
+        assertEquals(s:size(),2)
+        assertEquals(s:get(0),{1,2,3})
+        assertEquals(s:get(1),1)
+        s:set(1, 2)
+        assertEquals(s:size(),2)
+        assertEquals(s:get(0),{1,2,3})
+        assertEquals(s:get(1),2)
+        s:set(2, 3)
+        assertEquals(s:size(),2)
+        assertEquals(s:get(0),{1,2,3})
+        assertEquals(s:get(1),2)
+        assertIsNil(s:get(2))
+        assertError(s.set, s, "no", -1)
+        assertError(s.set, s, -1, 2)
+    end
+
+    function TestStack:test_set_op()
+        local s = Stack:new()
+        s:push(1)
+        s:push({1,2,3})
+        assertEquals(s:size(),2)
+        assertEquals(s:get(0),{1,2,3})
+        assertEquals(s:get(1),1)
+        s[1] = 2
         assertEquals(s:size(),2)
+        assertEquals(s:get(0),{1,2,3})
+        assertEquals(s:get(1),2)
+        s[0] = "new"
+        assertEquals(s:size(),2)
+        assertEquals(s:get(0),"new")
+        assertEquals(s:get(1),2)
+        s[1] = "old"
+        assertEquals(s:get(0),"new")
+        assertEquals(s:get(1),"old")
+        assertEquals(s:size(),2)
+        s[2] = "error"
+        assertEquals(s:get(0),"new")
+        assertEquals(s:get(1),"old")
+        assertIsNil(s:get(2))
+        assertEquals(s:size(),2)
+    end
+
+    function TestStack:test_list()
+        local s = Stack:new()
         local l = s:list()
+        assertEquals(#l, 0)
+        s:push(1)
+        s:push({1,2,3})
+        assertEquals(s:size(),2)
+        l = s:list()
         assertItemsEquals(l[1],{1,2,3})
         assertEquals(l[2],1)
+        assertEquals(s:size(),2)
     end
 
     function TestStack:test_tostring()
-        s = Stack:new()
+        local s = Stack:new()
         s:push(1)
         assertEquals(tostring(s), "{1}")
         s:push(2)