Explain the use of Go's type composition for creating complex data structures?

In Go, type composition allows us to create complex data structures by combining multiple types into a single new type. This is achieved by embedding one or more types within a struct type.

Here's an example to illustrate type composition in Go:

type Person struct {
    Name string
    Age int
}

type Employee struct {
    Person
    Id int
    Salary float64
}

func main() {
    emp := Employee{
        Person: Person{Name: "John Doe", Age: 30},
        Id: 1001,
        Salary: 50000.0,
    }
    fmt.Println(emp.Name, emp.Age, emp.Id, emp.Salary) // prints "John Doe 30 1001 50000"
}

In this example, we have a **Person** struct type with two fields **Name** and **Age**, and an **Employee** struct type that embeds the **Person** type and adds two more fields **Id** and **Salary**. By embedding the **Person** type within the **Employee** type, we can access its fields as if they were fields of the **Employee** type. This allows us to create a complex data structure that represents an employee with personal information and job-related details.

We can also override the fields of the embedded type by declaring a field with the same name in the embedding type. 

For example:

type Manager struct {
    Person
    Id int
    Salary float64
    Employees []Employee
}

func main() {
    mgr := Manager{
        Person: Person{Name: "Jane Doe", Age: 40},
        Id: 1002,
        Salary: 80000.0,
        Employees: []Employee{
            {Person: Person{Name: "Alice", Age: 25}, Id: 1003, Salary: 60000.0},
            {Person: Person{Name: "Bob", Age: 30}, Id: 1004, Salary: 55000.0},
        },
    }
    fmt.Println(mgr.Name, mgr.Age, mgr.Id, mgr.Salary, mgr.Employees) // prints "Jane Doe 40 1002 80000 [{Alice 25 1003 60000} {Bob 30 1004 55000}]"
}

In this example, we have a **Manager** struct type that embeds the **Person** type, but also overrides the **Id** and **Salary** fields. The **Manager** type also has a slice of **Employee** types as a field. By using type composition in this way, we can create complex data structures that are easy to use and maintain.

In summary, type composition in Go allows us to create complex data structures by embedding one or more types within a struct type. This allows us to reuse existing types and add new functionality to create more complex types.