code: function resolveHost (host) {
    const defaultHost = '0.0.0.0'
    host = host || defaultHost
    const displayHost = host === defaultHost
      ? 'localhost'
      : host
    return {
      displayHost,
      host
    }
  }
docs: Resolve host.
  
  @param {string} host user's host
  @returns {{displayHost: string, host: string}}