docs: function mapbox(address, options = Mapbox.Options) {
    // Define options
    const mode = options.mode || Mapbox.Options.mode
    const access_token = options.access_token || options.key || process.env.MAPBOX_ACCESS_TOKEN
    const country = options.country
    const limit = options.limit || Mapbox.Options.limit
  
    // Validation
    if (!access_token) { error('[options.access_token] is required') }
    if (['mapbox.places', 'mapbox.places-permanent'].indexOf(mode) === -1) { error('--mode is invalid') }
    if (country && iso3166.codes[country] === undefined) { error('--country is invalid') }
  
    // URL Parameters
    const params = {
      access_token,
      country,
      limit,
    }
  
    // Request
    const url = `https://api.mapbox.com/geocoding/v5/${mode}/${address}.json`
    return request(url, Mapbox.toGeoJSON, params, options)
  }