docs: function Pool(hosts, params) {
      if (typeof hosts === 'string') hosts = [hosts];
      this.hosts = hosts.map(host => {
          if (host.substr(0, 4) === 'http') {
              return URL.parse(host);
          } else {
              return URL.parse('http://' + host);
          }
      }).map(url => {
          return {
              protocol: (url['protocol'] === 'https:') ? https : http,
              host: url['hostname'],
              port: url['port'] || (url['protocol'] === 'http:' ? 80 : 443),
              auth: url['auth']
          };
      });
  
      this.params = {
          timeout: 10000,
          headers: {}
      };
      if (params && typeof params === 'object') {
          if (params.timeout) this.params['timeout'] = params.timeout;
          if (params.headers) this.params['headers'] = params.headers;
      }
  }