Functions and methods on types

Types without behavior can be limiting, and it's often the case that we want to have functions or methods on types so that we can return new instances of them rather than constructing them manually or so that we have the ability to the manipulate fields of a user-defined type. We can do this via impl blocks, which is read as providing implementations for a type. We can provide implementations for all user-defined types or any wrapper type. First, let's take a look at how to write implementations for a struct.