XAPIVerb: "answered" | "asked" | "attempted" | "attended" | "commented" | "completed" | "exited" | "experienced" | "failed" | "imported" | "initialized" | "interacted" | "launched" | "mastered" | "passed" | "preferred" | "progressed" | "registered" | "responded" | "resumed" | "scored" | "shared" | "suspended" | "terminated" | "voided" | "downloaded" | "copied" | "accessed-reuse" | "accessed-embed" | "accessed-copyright"