放弃已过时的库,采用抽象层次

运行时，我收到了许多警告： npm warn deprecated [email protected]: Superseded by abstract-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by abstract-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by abstract-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by browser-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by abstract-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by abstract-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by abstract-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by level-transcoder (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by abstract-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by abstract-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by abstract-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by classic-level (https://GitHub.com/Level/community#faq) npm warn deprecated [email protected]: Superseded by classic-level (https://GitHub.com/Level/community#faq)