internal suspend fun requireCapability(
    call: ApplicationCall,
    c: InternalCapability,
    block: suspend (InternalUserPrincipal) -> Unit
) {
    val principal = call.authentication.principal<InternalUserPrincipal>()!!
    if (!principal.capabilities.contains(c)) {
        logger.debug("Principal ${principal.internalUserId} did not have capability $c")
        call.respond(HttpStatusCode.Unauthorized)
        return
    }

    block(principal)
}

requireCapability(foo) { your logic here }