API requests are asynchronous. That means that if you do this:
const c = require('centra')
const getAPI = c('localhost:3000/api').send();
Then Node will fire off the request, but it will not wait for it to complete and will instead move straight on to logging the value of the getAPI variable, which will be undefined, as the request is still in progress.
One way around this is to use async...await, which will (as the name suggests) cause the runtime to wait for the result of an asynchronous operation.