diff --git a/LICENSE.txt b/LICENSE.txt
deleted file mode 100644
index f584954..0000000
--- a/LICENSE.txt
+++ /dev/null
@@ -1,21 +0,0 @@
-MIT License
-
-Copyright (c) [2020] [Reza Mobaraki] | MR.Rezoo
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
\ No newline at end of file
diff --git a/src/factory2.py b/src/factory2.py
index 46e4eb0..5631dfb 100644
--- a/src/factory2.py
+++ b/src/factory2.py
@@ -1,40 +1,54 @@
 """
-    Creational:
-        Factory method
-            3 Component => 1.Creator, 2.Product, 3.Client
+	Factory
+	- Factory is a creational design pattern that provides an interface for creating objects
+	in a superclass, but allows subclasses to alter the type of objects that will be created.
+
+	3 component => 1. creator, 2. product, 3. client
 """
-from abc import abstractmethod
+from abc import ABC, abstractmethod
 
 
-class File:
-    def __init__(self, name, file_format):
-        self.name = name
-        self.file_format = file_format
+class File(ABC):  # creator
+    def __init__(self, file):
+        self.file = file
 
+    @abstractmethod
+    def make(self):
+        pass
 
-class B:
+    def call_edit(self):
+        product = self.make()
+        result = product.edit(self.file)
+        return result
 
-    def edit(self, file):  # client
-        return self._get_edit(file)
 
-    def _get_edit(self, file):  # creator
-        if file.file_format == 'json':  # identifier
-            return self.json_edit(file)
-        elif file.file_format == 'xml':  # identifier
-            return self.xml_edit(file)
-        else:
-            raise ValueError("So Sorry. . .")
+class JsonFile(File):  # creator
+    def make(self):
+        return Json()
 
-    @abstractmethod
-    def json_edit(self, file):  # product
-        print(f"Editing Json File. . . {file.name}")
 
-    @abstractmethod
-    def xml_edit(self, file):  # product
-        print(f"Editing Xml File. . . {file.name}")
+class XmlFile(File):  # creator
+    def make(self):
+        return Xml()
+
+
+class Json:  # product
+    def edit(self, file):
+        return f'Working on {file} Json...'
+
+
+class Xml:  # product
+    def edit(self, file):
+        return f'Working on {file} Xml...'
+
+
+def client(file, format):  # client
+    formats = {
+        'json': JsonFile,
+        'xml': XmlFile
+    }
+    result = formats[format](file)
+    return result.call_edit()
 
 
-if __name__ == '__main__':
-    first_file = File('first', 'xml')
-    b1 = B()
-    b1.edit(first_file)
+print(client('show', 'xml'))
diff --git a/src/singleton2.py b/src/singleton2.py
index 2189d37..23a2b39 100644
--- a/src/singleton2.py
+++ b/src/singleton2.py
@@ -4,7 +4,7 @@
 """
 
 
-class Singleton(type):
+class Singleton1(type):
     _instance = None
 
     def __call__(cls, *args, **kwargs):
@@ -13,17 +13,36 @@ def __call__(cls, *args, **kwargs):
         return cls._instance
 
 
-class DB(metaclass=Singleton):
+class Singleton2(type):
+    """
+    Singleton metaclass
+    Based on Python Cookbook 3rd Edition Recipe 9.13
+    Only one instance of a class can exist. Does not work with __slots__
+    """
+
+    def __init__(self, *args, **kw):
+        super(Singleton2, self).__init__(*args, **kw)
+        self.__instance = None
+
+    def __call__(self, *args, **kw):
+        if self.__instance is None:
+            self.__instance = super(Singleton2, self).__call__(*args, **kw)
+        return self.__instance
+
+
+class DBMongo(metaclass=Singleton2):
+    pass
+
+class DBPostgres(metaclass=Singleton2):
     pass
 
 
 if __name__ == '__main__':
-    s1 = DB()
-    s2 = DB()
-    s3 = DB()
+    m1 = DBMongo()
+    m2 = DBMongo()
 
-    print(id(s1))
-    print(id(s2))
-    print(id(s3))
+    p1 = DBPostgres()
+    p2 = DBPostgres()
 
-    print(id(s1) == id(s2) == id(s3))
+    print(f"Mongo: {id(m1)} - {id(m2)} ", id(m1) == id(m2))
+    print(f"Postgres: {id(p1)} - {id(p2)} ", id(p1) == id(p2))