How to resolve this .map error in Socket programming angular?

问题

I am starting with socket programming in Angular from the link: https://www.npmjs.com/package/ngx-socket-io and I am getting error. Need help.

Error on hover:

Property 'map' does not exist on type 'Observable'

来源：https://stackoverflow.com/questions/59872472/how-to-resolve-this-map-error-in-socket-programming-angular