Note that the constructor for each derived class should call thebase class’s setUnits function. Also, you will need a virtualdestructor for Container. Test these classes thoroughly in the mainsource file by creating objects of all the derived classes on theheap and storing them in a vector as unique pointers to Containers.Test that you have overloaded == properly to allow programmers toprevent duplicates. Also test that you have overloaded the properoperator to allow the sort algorithm to sort all types ofcontainers by
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