Page 293 - Computer Science Class 11 Without Functions
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12.5 Heterogeneous List

            The items stored in the list can be of any type, such as numeric, string, Boolean, or list. For instance, a list  comprising
            student details, namely name, roll number, course, contact number, and marks in five subjects may be specified as follows:
             >>>  student = ['Rohan', 2304, 'B.Sc. Hons Computer Science', 9899410188, [99, 90, 85, 99, 100]]
             >>> for element in student:
             ...     print(element)
             ...
             ...

            Output:
                 Rohan
                 2304
                 B.Sc. Hons Computer Science
                 9899410188
                 [99, 90, 85, 99, 100]
            Note that the list student includes three types of objects, namely, str, int, and list.
            Next, we define another heterogeneous list mixedList:
             >>> mixedList = [1, [2, 3], 'three', 4.0]
            12.6 More Operations on Lists


            12.6.1 Concatenation Operator +

            The +  operator concatenates a pair of lists. The concatenated list comprises the elements of the first list on the
            left-hand side of the + operator, followed by the elements of the second list on the right-hand side of the + operator.
             >>> lst1 = ['Red', 'Green']
             >>> lst2 = ['Blue']
             >>> print('id(lst1): ', id(lst1))
                 id(lst1):  3237079561600
             >>> print('id(lst2): ', id(lst2))
                 id(lst2):  3237079384384
             >>> lst1 = lst1 + lst2
             >>> lst1
                 ['Red', 'Green', 'Blue']
             >>> print('id(lst1): ', id(lst1))
                 id(lst1):  3237079385664
            Note that the concatenation operator creates a new object for the concatenated list.

            We have seen above that the assignment
            lst1 = lst1 + lst2
            creates a new object which is assigned to lst1. However, the Python operator +=  updates the existing list lst1. For
            example,

             >>> lst1 = [10, 5, 20]
             >>> lst2 = [9, 7]
             >>> print('id(lst1): ', id(lst1))
                 id(lst1):  3237079560384
             >>> lst1 += lst2
             >>> lst1
                 [10, 5, 20, 9, 7]
             >>> print('id(lst1): ', id(lst1))
                 id(lst1):  3237079560384
            Now we understand the concatenation of python lists, it is time to introduce the comparison operators is and is
            not which are used to check whether two variables refer to the same object or not. They return True if the variables
            refer to the same object and False otherwise.


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