How to use the simple-get.head function in simple-get

if (err) {
          // Browsers allow HTTP redirects for simple cross-origin
          // requests but not for requests that require preflight.
          // Use a simple request to unravel any redirects and get the
          // final URL.  Retry the original request with the new URL if
          // it's different.
          //
          // This test is imperfect but it's simple and good for common
          // cases.  It catches all cross-origin cases but matches a few
          // same-origin cases too.
          if (typeof window === 'undefined' || url.startsWith(`${window.location.origin}/`)) {
            hasError = true
            return cb(err)
          }

          return get.head(url, (errHead, res) => {
            if (hasError) return
            if (errHead) {
              hasError = true
              return cb(errHead)
            }
            if (res.statusCode < 200 || res.statusCode >= 300) {
              hasError = true
              return cb(new Error(`Unexpected HTTP status code ${res.statusCode}`))
            }
            if (res.url === url) {
              hasError = true
              return cb(err)
            }

            opts.url = res.url
            get.concat(opts, (err, res, data) => {

if (err) {
        // Browsers allow HTTP redirects for simple cross-origin
        // requests but not for requests that require preflight.
        // Use a simple request to unravel any redirects and get the
        // final URL.  Retry the original request with the new URL if
        // it's different.
        //
        // This test is imperfect but it's simple and good for common
        // cases.  It catches all cross-origin cases but matches a few
        // same-origin cases too.
        if (typeof window === 'undefined' || url.startsWith(window.location.origin + '/')) {
          hasError = true
          return cb(err)
        }

        return get.head(url, function (errHead, res) {
          if (hasError) return
          if (errHead) {
            hasError = true
            return cb(errHead)
          }
          if (res.statusCode < 200 || res.statusCode >= 300) {
            hasError = true
            return cb(new Error('Unexpected HTTP status code ' + res.statusCode))
          }
          if (res.url === url) {
            hasError = true
            return cb(err)
          }

          opts.url = res.url
          get.concat(opts, function (err, res, data) {

return function (cb) {
      get.head(REGISTRY_URL + name, function (err, res) {
        if (err) return cb(err)
        if (res.statusCode === 404) next(null, name)
        res.resume() // consume the stream
        cb(null)
      })
    }
  })

return function (cb) {
    console.log('checking ' + pkg.repo + '...')
    get.head(pkg.repo, function (err, res) {
      if (res.statusCode !== 200) {
        err = new Error('Non-200 status code ' + res.statusCode)
      }
      if (err) {
        err.message = pkg.name + ': ' + err.message
        cb(err)
      } else {
        cb(null)
      }
    })
  }
}), function (err) {