Error: Cannot find module 'documentation'

I am trying to use the API. I installed documention.js (13.2.5) using npm (6.14.16) and it is working fine from the command line. However this does not generate a module in node_modules and when I run a program with

var documentation = require('documentation');

I get

Error: Cannot find module 'documentation'

How do I install the module. I can't find instructions in the documentation..