How to use one class in another class that is in the same package?

I'm fairly new to Go and I'm making an a small flashcards app.
My package structure is this

VocabHelper
|
-|src
--|com
---|wks
----|card
------Card.go
------Deck.go
----|main
------main.go

Deck and Card are two separate classes but they're in the same package:

Card.go

package card
type Card struct{
	Question string
	Answer string
}

Deck.go

package card
import (
	"math/rand"
)
type Deck struct{
	Cards []card.Card
}

When I try to compile the project, the compiler says undefined:card even though card is in the same package as deck. How can I use the card class in the deck class?

Leave off the card. part, and it should work. They're both in the same package.

type Deck struct{
   Cards []Card
}