diff --git a/plugin/ExtensionTree.lua b/lua/SpecSwitcher/ExtensionMap.lua
similarity index 73%
rename from plugin/ExtensionTree.lua
rename to lua/SpecSwitcher/ExtensionMap.lua
index 2051cb4..c4225e7 100644
--- a/plugin/ExtensionTree.lua
+++ b/lua/SpecSwitcher/ExtensionMap.lua
@@ -1,14 +1,13 @@
+local ExtMap = {}
 
-ExtTree = {}
-
-function ExtTree:new (o)
+function ExtMap:new (o)
     o = o or {}
     setmetatable(o, self)
     self.__index = self
     return o
 end
 
-function ExtTree:add_single (in_ext, out_ext)
+function ExtMap:add_single (in_ext, out_ext)
     if self[in_ext] ~= nil then
         if type(out_ext) == "table" then
             for _, out in ipairs(out_ext) do
@@ -26,7 +25,7 @@ function ExtTree:add_single (in_ext, out_ext)
     end
 end
 
-function ExtTree:add_multiple (in_exts, out_exts)
+function ExtMap:add (in_exts, out_exts)
     if type(in_exts) == "table" then
         for _, in_ext in ipairs(in_exts) do
             self:add_single( in_ext, out_exts)
@@ -44,7 +43,7 @@ function ExtTree:add_multiple (in_exts, out_exts)
     end
 end
 
-function ExtTree:print ()
+function ExtMap:print ()
     base = "%s -> "
     for I in pairs(self) do
         local in_map = string.format(base, I)
@@ -55,12 +54,4 @@ function ExtTree:print ()
     end
 end
 
-p1 = ExtTree:new(nil)
-
-p1:add_multiple("h", {"c", "cpp", "cxx", "cc", "CC"})
-p1:add_multiple("H", {"C", "CPP", "CXX", "CC"})
-p1:add_multiple("hpp", {"cpp", "c"})
-p1:add_multiple("HPP", {"CPP", "C"})
-p1:add_multiple("ads", "adb")
-
-p1:print()
+return ExtMap