Describes the cause and action for error messages.
Error Message(English)：
is not defined in node js
req is not defined in node.js API method : node - Reddit
https://www.reddit.com/r/node/comments/7sc49j/req_is_not_defined_in_nodejs_api_method/
tgorka (Tomasz Gorka) / Repositories ・ GitHub
https://github.com/tgorka?tab=repositories
is defined - npms
https://npms.io/search?q=is%20defined
User Andrew Newdigate - Stack Exchange
https://stackexchange.com/users/20832/andrew-newdigate