What is errors.As primarily used for?

What is printed by the following Go code?

s := []int{10, 20, 30, 40}
x := s[1:3]
fmt.Print(len(x), cap(x))

What should long-running work normally do when its associated context is cancelled?

What is a primary purpose of context.Context in Go server applications?

Given the following declarations, which statement is correct?

type Writer interface {
    Write([]byte) error
}
type File struct{}
func (f File) Write(data []byte) error {
    return nil
}

What is httptest.NewRecorder commonly used for?

What is errors.Is primarily used for?

What problem can occur when multiple goroutines access the same shared data concurrently and at least one access is a write, without appropriate synchronization?

What is printed by the following Go code?

x := 10
p := &x
*p = 20
fmt.Print(x)

What is the effect of a default case in a select statement when no communication case can proceed?