ABSTRACT
If you look at an apple and an orange, you will see that they are alike in some ways. They are both round, and they have a skin and pips. But in other ways they are different. An orange has segments but an apple does not, and they are different colours. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203422366/3a3f7722-457a-4714-bdd2-4343b048d293/content/f0009-02_C.jpg" xmlns:xlink="https://www.w3.org/1999/xlink"/>
