Now that you've seen how to create immutable geometries, let's go over the other ways of creating them so that they are mutable (they can be changed after they've been created). The primary reason you'd use these builders is so that a user can change the geometry interactively by adding, inserting, or removing parts of a polygon, for example, or by using a mouse, finder, or pen. Other than that, the class hierarchy is the same as shown in class diagram, in the Geometric objects section. However, as you can change these geometries, there are some other properties and methods. For example, MapPointBuilder has a method named SetValue that takes in x and y, and optionally, z values, so that you can change a point (vertex) of a polygon. The MultipartBuilder class allows you to get and set PartCollection that makes up the Multipart class. A Multipart class allows you to only get RealOnlyPartCollection. Also, MultipartBuilder has several methods, such as AddPart and AddPoint, which allow you to add geometries to it.