const usersCursor = Users.find({}).cursor() // go though the entire collection

usersCursor.pipe(through(function (user) {
    this.pause()

    Users.find({$or: [
        // Find users with similar username or email
        {nam: new RegExp(similarUsernameRegexp(user.nam), 'i')},
        {email: new RegExp(similarEmailRegexp(user.email), 'i')}
    ]}, (err, users) => {
        if (err) {
            console.error(err)
            this.emit('error', err)
            return this.resume()
        }

        if (users.length > 1) {
            // Add users who have similarities with at least one other
            const row = {
                USERNAME: user.nam,
                EMAIL: user.email,
                'FIRST NAME': user.firstName,
                'LAST NAME': user.lastName
            }

            this.queue(row)
        }

        this.resume()
    })

}, function (err) {
    if (err) {
        console.log(err)
    }

    this.queue(null)

    // Was hoping to be done with all of the User lookups at this point,
    // also of note the next stage in the pipeline never receives the last user.
}))
// build a document from the results
.pipe(csvBuilder.createTransformStream())