diff --git a/PPL-assignment/python_oop.py b/PPL-assignment/python_oop.py
new file mode 100644
index 0000000..9d03f5b
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+++ b/PPL-assignment/python_oop.py
@@ -0,0 +1,199 @@
+'''polymorphism is implemented using method overloading, method-overriding, operator overloading and duck-typing
+also concepts like base class, derived classes implemented also inheritance is implemented'''
+
+class shapes(): #This is base class
+    def perimeter(self): # this method is 'methodoverided' in all inherited classes
+        pass
+    
+class _2d_shapes(shapes): #sub-class of shapes
+    def area(self): # method-overriding
+        pass
+    def __gt__(self, p): #operator overloading
+        if(self.area() >= p.area()):
+            return True
+        else:
+            return False
+    def __lt__(self, p): #operator overloading
+        if(self.area() >= p.area()):
+            return False
+        else:
+            return True
+    def __add__(self, p): #operator overloading for adding area.
+        return self.area()+p.area()
+    
+    
+class _3d_shapes(shapes):#sub-class of shapes
+    def volumn(self):
+        pass
+    def surface_area(self):
+        pass
+    def __gt__(self, p): #operator overloading
+        if(self.surface_area() >= p.surface_area()):
+            return True
+        else:
+            return False
+    def __lt__(self, p): #operator overloading
+        if(self.surface_area() >= p.area()):
+            return False
+        else:
+            return True  
+    def __add__(self, p): #operator overloading for adding surface_area.
+        return self.surface_area()+p.surface_area()
+    
+class triangle(_2d_shapes): #inherited from 2d-shapes
+    def __init__(self, a = 3, b = 4, c = 5):
+        self.a = a
+        self.b = b
+        self.c = c
+        
+    def perimeter(self):
+        return self.a+self.b+self.c
+    
+    def area(self):
+        a = self.a
+        b = self.b
+        c = self.c
+        s =  (a+b+c)/2
+        return (s*(s-a)*(s-b)*(s-c))**(0.5)
+
+    def get(self, how_many=None):#method overloading is implemented
+        if(how_many==1):
+            return self.a
+        elif(how_many==2):
+            return self.b
+        else:
+            return self.a, self.b, self.c
+
+    def set(self,a,b,c):
+        self.a = a
+        self.b = b
+        self.c = c
+
+class square(_2d_shapes):
+    def __init__(self, side = 5):
+        self.side = side
+        
+    def perimeter(self):
+        return 4*self.side
+    
+    def area(self):
+        return self.side*self.side
+    
+    def get(self):
+        return self.side
+
+    def set(self,side):
+        self.side = side
+        
+class circle(_2d_shapes):
+    def __init__(self, radius = 5):
+        self.r = radius
+        
+    def perimeter(self):
+        return 2*3.142*self.r
+    
+    def area(self):
+        return 3.142*self.r*self.r
+    
+    def get(self):
+        return self.r
+
+    def set(self, radius):
+        self.r = radius
+        
+class rectangle(_2d_shapes):
+    def __init__(self, a = 5, b = 3):
+        self.a = a
+        self.b = b
+        
+    def perimeter(self):
+        return (2*self.a)+(2*self.b)
+    
+    def area(self):
+        return self.a*self.b
+    
+    def get(self, what=None): #method overloading is implemented
+        if(what=="length"):
+            return self.a
+        elif(what=="breadth"):
+            return self.b
+        else:
+            return self.a, self.b
+
+    def set(self,a,b):
+        self.a = a
+        self.b = b
+
+class cube(_3d_shapes): #inherited from 3d-shapes
+    def __init__(self, side = 5):
+        self.side = side
+        
+    def perimeter(self):
+        return 6*self.side
+    
+    def volumn(self):
+        return self.side**3
+    
+    def surface_area(self):
+        return 6*(self.side**2)
+    
+    def get(self):
+        return self.side
+
+    def set(self,side):
+        self.side = side
+
+class sphere(_3d_shapes):
+    def __init__(self, r = 5):
+        self.r = r
+        
+    def volumn(self):
+        return (4/3)*3.142*(self.r**3)
+    
+    def surface_area(self):
+        return 4*3.142*(self.r**2)
+    
+    def set(self, r):
+        self.r = r
+        
+    def get(self):
+        return self.r
+    
+class cylinder(_3d_shapes):
+    def __init__(self, r = 5, h = 7):
+        self.r = r
+        self.h = h
+        
+    def volumn(self):
+        return 3.142*(self.r**2)*self.h
+    
+    def surface_area(self):
+        return (2*3.142*self.r)*(self.r+self.h)
+    
+    def set(self, r, h):
+        self.r = r
+        self.h = h
+        
+    def get(self, what=None): #method overloading is implemented
+        if(what=="radius"):
+            return self.r
+        elif(what=="height"):
+            return self.h
+        else:
+            return self.r, self.h
+        
+a=triangle()
+b=square()
+print(a+b)
+
+if(a < b):
+    print("TRUE")
+else:
+    print("False")
+    
+c = cylinder()
+d = c.get("height")
+print(d)
+
+d = c.get()
+print(d)