What are context values primarily intended for?

Which description best matches a goroutine leak?

What happens when this send operation is reached?

var ch chan int
ch <- 1

What guarantee does sync.Once provide for calls to its Do method on the same Once value?

What is printed by the following Go code?

type MyError struct{}
func (*MyError) Error() string { return "error" }
var p *MyError = nil
var err error = p
fmt.Println(err == nil)

Why is err not nil in the following code?

var p *MyError = nil
var err error = p

What happens to the Password field during JSON marshaling?

type User struct {
    Name     string `json:"name"`
    Password string `json:"-"`
}

Why should an HTTP response body obtained from http.Client normally be closed?

When are the arguments of a deferred function call evaluated?

Which expression idiomatically adds context to err while preserving it for errors.Is and errors.As?