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Next, consider the assignment:

         >>> lst1[4] = 100
         >>> lst1
              [30, 60, 10, 20, 100]
         >>> id(lst1)
              1933477279552
        Note that lst1 and lst2 still refer to the same object, as further illustrated below:
         >>> lst2
              [30, 60, 10, 20, 100]
         >>> id(lst2)
              1933477279552
        Each of the variables lst1 and lst2 refers to the same modified list object.














                      Fig 4.7: Variables lst1 and lst2 refer to the same list object (object id  1933477279552)
        Finally, examine the following:
         >>> lst1 = [3, 4, 2, 1]
         >>> id(lst1)
                  2353324714816
         >>> id(lst2)
                  1933477279552
        Note  that assigning  the variable  lst1  to  a  new  list  object  (indeed,  it  could  as  well  be  an  object  of  some
        other type) changes its object id.  As expected, the assignment of the list object [3,  4,  2,  1] to the variable
        lst1, did not impact the variable lst2, which continues to refer to the list [30, 60, 10, 20, 100] (object id
        1933477279552).

















                                   Fig 4.8: The variables lst1 and lst2 refer to different objects


        4.3 Visualising Execution of Python Code

        To visualise the execution of Python code, online tool PythonTutor may be used through following link:
        http://www.pythontutor.com/visualize.html#mode=display

        It is a graphical interface for visualising a program's execution step by step. Fig 4.9 shows the Python Tutor interface.
        To get started, you need to select the Python version in the dropdown menu for the code.





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