/** @private */
 scopeDisconnected(scope: Scope) {
   this.scopesByIdentifier.delete(scope.identifier, scope)
   const module = this.modulesByIdentifier.get(scope.identifier)
   if (module) {
     module.disconnectContextForScope(scope)
   }
 }

  private refreshTokensForElement(element: Element): [Token[], Token[]] {
    const previousTokens = this.tokensByElement.getValuesForKey(element)
    const currentTokens = this.readTokensForElement(element)
    const firstDifferingIndex = zip(previousTokens, currentTokens)
      .findIndex(([previousToken, currentToken]) => !tokensAreEqual(previousToken, currentToken))

    if (firstDifferingIndex == -1) {
      return [[], []]
    } else {
      return [previousTokens.slice(firstDifferingIndex), currentTokens.slice(firstDifferingIndex)]
    }
  }

 private tokenUnmatched(token: Token) {
   this.delegate.tokenUnmatched(token)
   this.tokensByElement.delete(token.element, token)
 }

 private tokenMatched(token: Token) {
   this.delegate.tokenMatched(token)
   this.tokensByElement.add(token.element, token)
 }

 elementUnmatchedAttribute(element: Element) {
   this.tokensUnmatched(this.tokensByElement.getValuesForKey(element))
 }

 private connectModule(module: Module) {
   this.modulesByIdentifier.set(module.identifier, module)
   const scopes = this.scopesByIdentifier.getValuesForKey(module.identifier)
   scopes.forEach(scope => module.connectContextForScope(scope))
 }