How to use the http-call.HTTP function in http-call

let app = require('../lib/server')
let request = require('supertest').agent(app.listen())
let user = require('../lib/user')
let redis = require('../lib/redis')
let co = require('co')
let url = require('url')
let crypto = require('crypto')
let fs = require('fs')
let config = require('../lib/config')
let expect = require('unexpected')
let sinon = require('sinon')
let http = require('http-call').HTTP
let storageBackends = require('./_storage_backends')

// make sure this user is in the htpasswd file
const testUser = {name: 'test', password: 'test'}

function * deleteItems (prefix) {
  let items = yield config.storage.list(prefix)
  for (let item of items) {
    console.log(`deleting ${item}`)
    yield config.storage.delete(item)
  }
}

function bearer (token) {
  return function (request) {
    request.set('Authorization', `Bearer ${token}`)

const http = require('http-call').HTTP
const maxRetries = 10

async function call (url, out, retries) {
  try {
    let {response} = await http.stream(url)
    response.on('data', function (d) {
      out.write(d)
    })
    return await new Promise(function (resolve, reject) {
      response.on('error', reject)
      response.on('end', resolve)
    })
  } catch (err) {
    if (err.statusCode === 404 && retries <= maxRetries) {
      return new Promise(function (resolve, reject) {
        setTimeout(function () {