Another powerful feature that we briefly covered in Chapter 3, One Piece at a Time – Types, Scopes, and Projects is the ability to extend existing types. We saw that we could add an extension to the string type that would allow us to repeat the string multiple times. Let's look at a more practical use case for this and discuss its benefits in terms of improving our code.
Perhaps we are creating a grade-tracking program where we are going to be printing out a lot of percentages. A great way to represent percentages is by using a float with a value between zero and one. Floats are great for percentages because we can use the built-in math functions and they can represent pretty granular numbers. The hurdle to cross when using a float to represent a percentage is printing it out. If we simply print out the value, it will most likely not be formatted the way we would want. People prefer percentages to be out of 100 and have a percent symbol after it.
Worst...
