diff --git a/JavaScript/2-speed.js b/JavaScript/2-speed.js
index de89ff8..aca41d3 100644
--- a/JavaScript/2-speed.js
+++ b/JavaScript/2-speed.js
@@ -3,14 +3,15 @@
 const LOOP = 10000;
 
 function memoize(fn) {
-  const cache = {};
+  const cache = new Map();
   return (...args) => {
     const key = args + '';
-    const val = cache[key];
-    if (val) return val;
+    if (cache.has(key)) {
+      return cache.get(key);
+    }
     else {
       const res = fn(...args);
-      cache[key] = res;
+      cache.set(key, res);
       return res;
     }
   };
@@ -20,7 +21,8 @@ let fib = n => (n <= 2) ? 1 : fib(n - 1) + fib(n - 2);
 
 function speedTest(name, fn, args, count) {
   let start = new Date().getTime();
-  for (let i = 0; i < count; i++) {
+  let i; //or use "var" in for(...). (no)
+  for (i = 0; i < count; i++) {
     fn(...args);
   }
   let end = new Date().getTime();
@@ -28,6 +30,12 @@ function speedTest(name, fn, args, count) {
   console.log(`${name} * ${count} : ${time}`);
 }
 
+speedTest('fib(10)', fib, [10], LOOP);
+speedTest('fib(15)', fib, [15], LOOP);
 speedTest('fib(20)', fib, [20], LOOP);
+speedTest('fib(25)', fib, [25], LOOP);
 fib = memoize(fib);
+speedTest('memoized fib(10)', fib, [10], LOOP);
+speedTest('memoized fib(15)', fib, [15], LOOP);
 speedTest('memoized fib(20)', fib, [20], LOOP);
+speedTest('memoized fib(25)', fib, [25], LOOP);
\ No newline at end of file
diff --git a/Python/1-fibonacci-simple.py b/Python/1-fibonacci-simple.py
new file mode 100644
index 0000000..9b5ba88
--- /dev/null
+++ b/Python/1-fibonacci-simple.py
@@ -0,0 +1,15 @@
+def fib(n):
+    if n == 0:
+        return 0
+    elif n == 1:
+        return 1
+    else:
+        return fib(n-1) + fib(n-2)
+
+print('fib(0): ', fib(0))
+print('fib(1): ', fib(1))
+print('fib(3): ', fib(3))
+print('fib(7): ', fib(7))
+print('fib(10): ', fib(10))
+
+print('fib(40): ', fib(40)) # here is a problem
diff --git a/Python/2-fibonacci-memoize.py b/Python/2-fibonacci-memoize.py
new file mode 100644
index 0000000..47226d5
--- /dev/null
+++ b/Python/2-fibonacci-memoize.py
@@ -0,0 +1,20 @@
+def memoize(f):
+    cache = {}
+    def inMemo(x):
+        if x not in cache:            
+            cache[x] = f(x)
+        return cache[x]
+    return inMemo
+    
+
+def fib(n):
+    if n == 0:
+        return 0
+    elif n == 1:
+        return 1
+    else:
+        return fib(n-1) + fib(n-2)
+
+
+fib = memoize(fib)
+print('fib(40): ', fib(40))
diff --git a/Python/3-fibonacci-decorator.py b/Python/3-fibonacci-decorator.py
new file mode 100644
index 0000000..6070e83
--- /dev/null
+++ b/Python/3-fibonacci-decorator.py
@@ -0,0 +1,20 @@
+def memoize(f):
+    cache = {}
+    def inMemo(x):
+        if x not in cache:            
+            cache[x] = f(x)
+        return cache[x]
+    return inMemo
+    
+
+@memoize
+def fib(n):
+    if n == 0:
+        return 0
+    elif n == 1:
+        return 1
+    else:
+        return fib(n-1) + fib(n-2)
+
+
+print('fib(40): ', fib(40))
diff --git a/Python/4-fibonacci-class.py b/Python/4-fibonacci-class.py
new file mode 100644
index 0000000..b4874c5
--- /dev/null
+++ b/Python/4-fibonacci-class.py
@@ -0,0 +1,26 @@
+class Memoize:
+    def __init__(self, func):
+        self.func = func
+        self.cache = {}
+    def __call__(self, *args):
+        if args not in self.cache:
+            self.cache[args] = self.func(*args)
+        return self.cache[args]
+
+@Memoize
+def fib(n):
+    if n == 0:
+        return 0
+    elif n == 1:
+        return 1
+    else:
+        return fib(n-1) + fib(n-2)
+
+
+print('fib(0): ', fib(0))
+print('fib(1): ', fib(1))
+print('fib(3): ', fib(3))
+print('fib(7): ', fib(7))
+print('fib(10): ', fib(10))
+
+print('fib(40): ', fib(40))
diff --git a/Python/5-memoize-file.py b/Python/5-memoize-file.py
new file mode 100644
index 0000000..de78d03
--- /dev/null
+++ b/Python/5-memoize-file.py
@@ -0,0 +1,34 @@
+import os, pickle
+from functools import wraps
+
+def memoize(fn):
+    if os.path.exists('memoize.pkl'):
+        print('Reading cache file!')
+        with open('memoize.pkl') as f:
+            cache = pickle.load(f)
+    else:
+        cache = {}
+
+    @wraps(fn)
+    def wrap(*args):
+        if args not in cache:
+            print('Running function with argument', args[0])
+            cache[args] = fn(*args)
+            # update the cache file
+            with open('memoize.pkl', 'wb') as f:
+                pickle.dump(cache, f)
+        else:
+            print('Result in cache!')
+        return cache[args]
+    return wrap
+
+@memoize
+def sqrt(x):
+    return x**2
+
+
+print(sqrt(5))
+print(sqrt(5))
+print(sqrt(7))
+print(sqrt(5))
+print(sqrt(7))
diff --git a/Python/6-memoize-lru.py b/Python/6-memoize-lru.py
new file mode 100644
index 0000000..6da5323
--- /dev/null
+++ b/Python/6-memoize-lru.py
@@ -0,0 +1,13 @@
+import functools
+
+@functools.lru_cache()
+def fib_lru(n):
+    if n in (0, 1):
+        return n
+    else:
+        return fib_lru(n - 2) + fib_lru(n - 1)
+
+print('fib_lru(0): ', fib_lru(0))
+print('fib_lru(7): ', fib_lru(7))
+print('fib_lru(10): ', fib_lru(10))
+print('fib_lru(40): ', fib_lru(40))
diff --git a/Python/memoize.pkl b/Python/memoize.pkl
new file mode 100644
index 0000000..12be9f8
Binary files /dev/null and b/Python/memoize.pkl differ