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L.insert(0, "abc")              ['abc', 10, 40, 20, 30]

                          print(L)
                          a = "xyz"                       ['abc', 10, 40, 'xyz', 20, 30]
                          L.insert(3, a)

                          print(L)
                          L.insert(5, ["a", "b"])         ['abc', 10, 40, 'xyz', 20, ['a', 'b'], 30]

                          print(L)

        Modifying Existing Values in a List

        List is mutable so data can be easily modified by overwriting a new value to an existing value in a given list by
        using an assignment operator (=). Syntax to modify existing values in a list is:
          list[index] = newvalue
        Example:

                                    Commands                             Output

                          l1=[10,20,40,50]                [10, 20, 40, 100]
                          l1[3]=100

                          print(l1)
                          l1[1:3]=["abc","xyz"]           [10, 'abc', 'xyz', 100]
                          print(l1)

        Removing Elements from a List

        There are two different functions used to remove elements in an existing list remove() and pop(). Let us learn
        about these functions in detail.

        The remove( ) Function
        The remove() function removes the first occurrence of the element with the specified value. It means only
        one value can be removed at a time even if there are duplicate values in the list. If you wish to remove multiple
        values then this function can be used within a loop where it repeats itself a specific number of times. Syntax of
        the remove() function is:

           list.remove(<single value>)
        For example,

                                    Commands                                      Output
                 marks = [23, 34, 23, 45, 56, 78, 56]              marks = [34, 23, 45, 56, 78, 56]
                 marks.remove(23)
                 print(marks)
                 marks.remove(56)                                  marks = [34, 23, 45, 78, 56]

                 print(marks)
                 marks.remove(72)                                  ValueError: list.remove(x): x not in list




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