public class Person { public string name; public void AddAge() { TypeBuilder builder = DynamicType.CreateTypeBuilder(typeof(Person)); builder.AddField("age", typeof(int)); } }In this example, we are using the TypeBuilder class to create a new type builder initialized with the Person class. We then use the AddField method to add a new field called "age" with a data type of int. This functionality may be included in some library packages, such as System.Reflection.Emit, System.Runtime.CompilerServices, or System.CodeDom.Compiler.