old_contents: import fetch from 'isomorphic-fetch'
  
  import config from './config'
  
  
  async function fetchJson(url, options) {
    const response = await fetch(url, options)
    if (response.status < 200 || response.status >= 300) {
      throw new Error(`'${url}' returned the unexpected return code: '${response.status}'.`)
    }
    const data = await response.json()
    return {
      data,
      'country-package': response.headers.get('country-package'),
      'country-package-version': response.headers.get('country-package-version'),
    }
  }
  
  
  export function fetchParameters(apiBaseUrl = config.apiBaseUrl) {
    return fetchJson(`${apiBaseUrl}/parameters`)
  }
  
  export function fetchVariables(apiBaseUrl = config.apiBaseUrl) {
    return fetchJson(`${apiBaseUrl}/variables`)
  }
  
  export function fetchParameter(parameterId, apiBaseUrl = config.apiBaseUrl) {
    return fetchJson(`${apiBaseUrl}/parameter/${parameterId}`)
  }
  
  export function fetchVariable(variableId, apiBaseUrl = config.apiBaseUrl) {
    return fetchJson(`${apiBaseUrl}/variable/${variableId}`)
  }
  
  export function fetchSwagger(apiBaseUrl = config.apiBaseUrl) {
    return fetchJson(`${apiBaseUrl}/spec`)
  }
  
new_contents: import fetch from 'isomorphic-fetch'
  
  import config from './config'
  
  
  async function fetchJson(url, options) {
    const response = await fetch(url, options)
      .catch(() => { throw new Error(`Could not fetch '${url}'.`)})
    if (response.status < 200 || response.status >= 300) {
      throw new Error(`'${url}' returned the unexpected return code: '${response.status}'.`)
    }
    const data = await response.json()
    return {
      data,
      'country-package': response.headers.get('country-package'),
      'country-package-version': response.headers.get('country-package-version'),
    }
  }
  
  
  export function fetchParameters(apiBaseUrl = config.apiBaseUrl) {
    return fetchJson(`${apiBaseUrl}/parameters`)
  }
  
  export function fetchVariables(apiBaseUrl = config.apiBaseUrl) {
    return fetchJson(`${apiBaseUrl}/variables`)
  }
  
  export function fetchParameter(parameterId, apiBaseUrl = config.apiBaseUrl) {
    return fetchJson(`${apiBaseUrl}/parameter/${parameterId}`)
  }
  
  export function fetchVariable(variableId, apiBaseUrl = config.apiBaseUrl) {
    return fetchJson(`${apiBaseUrl}/variable/${variableId}`)
  }
  
  export function fetchSwagger(apiBaseUrl = config.apiBaseUrl) {
    return fetchJson(`${apiBaseUrl}/spec`)
  }
  
subject: Improve error is API is dead