From f52fe43ba3bea5e9f5091445513279f800494760 Mon Sep 17 00:00:00 2001
From: Simeon Simeonov
Date: Mon, 7 Nov 2022 05:50:13 +0100
Subject: Update notebooks/python/python_3_8_to_3_11.ipynb and
 notebooks/python/python_oo.ipynb

---
 notebooks/python/python_oo.ipynb | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

(limited to 'notebooks/python/python_oo.ipynb')

diff --git a/notebooks/python/python_oo.ipynb b/notebooks/python/python_oo.ipynb
index 9f0774a..fe717a9 100644
--- a/notebooks/python/python_oo.ipynb
+++ b/notebooks/python/python_oo.ipynb
@@ -735,7 +735,7 @@
     "In object-oriented programming, inheritance is the mechanism of basing an object or class upon another object (prototype-based inheritance) or class (class-based inheritance), retaining similar implementation. Also defined as deriving new classes (sub classes) from existing ones such as super class or base class and then forming them into a hierarchy of classes.\n",
     "\n",
     "In most class-based object-oriented languages, an object created through inheritance, a \"child object\", acquires all the properties and behaviors of the \"parent object\" , with the exception of: constructors, destructor, overloaded operators and friend functions of the base class.  \n",
-    "Inheritance allows programmers to create classes that are built upon existing classes, to specify a new implementation while maintaining the same behaviors (realizing an interface), to reuse code and to independently extend original software via public classes and interfaces.\n",
+    "Inheritance allows programmers to create classes that are built upon existing classes, to specify a new implementation while maintaining the same behaviors (realizing an interface), to reuse code and to independently extend original software via public classes and interfaces. It is a \"is-a\" relationship between base (parent) class and a derived (child) class.\n",
     "\n",
     "One can simply view inheritance as a tool for code reuse.\n",
     "\n",
@@ -1048,7 +1048,13 @@
     "\n",
     "Not all classes admit a linearization. There are cases, in complicated hierarchies, where it is not possible to derive a class such that its linearization respects all the desired properties.  \n",
     "`TypeError: Cannot create a consistent method resolution order (MRO) for bases X, Y` is raised then.\n",
-    "\n"
+    "\n",
+    "\n",
+    "## The Liskov substitution principle (LSP):\n",
+    "\n",
+    "Functions that use references to base class objects must be able to use objects of derived classes without knowing it.\n",
+    "\n",
+    "In other words: an object (such as a class) may be replaced by a sub-object (such as a class that extends the first class) without breaking the program.\n"
    ]
   },
   {
-- 
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