Explain the concept of metaprogramming in Groovy and provide an example of how it can be used.

Metaprogramming in Groovy refers to the ability to modify and extend the behavior of the language itself or the behavior of existing classes at runtime. It allows developers to dynamically add, modify, or remove methods, properties, and other code artifacts during program execution. Metaprogramming in Groovy is made possible by its dynamic nature and powerful reflection capabilities. One of the key features of metaprogramming in Groovy is the ability to handle method invocations that are not explicitly defined. This feature is known as "method missing" and allows developers to intercept method calls for which there is no corresponding method definition. By implementing the `methodMissing` method in a class or using the `@Mixin` ann....