TypeError: keystone.mount is not a function

[ZeeAzmat]

unable to mount application

I am trying to upgrade my application from keystone 0.3 to 4.2 and when i did update the keystone version and installed node_modules I started getting this error while mounting the application. The documentation says mounting process has been rewritten - https://v4.keystonejs.com/guides/v-0-3-to-v-4-0-upgrade-guide/

It directs me towards admin/server in the modules, I did go through that as well but still couldn't find any help. I would highly appreciate any help on this.

Thanks

[ZeeAzmat]

@raveling Any help on this?