code: function scanWiFi() {
      return new Promise((ac) => {
          // WiFi scan
          exec('nmcli dev wifi list', (err, stdout, stderr) => {
              // eslint-disable-next-line max-len
              if (err) log('Cannot scan Wifi APs (possibly because "nmcli dev wifi list" command requires sudo?)');
              let lines = stdout.split('\n');
              const aps = [];
              lines.shift();
              lines.forEach((line)=>{
                  let li = line.indexOf('Infra');
                  if (li==-1) li = line.indexOf('インフラ');
                  if (li==-1) return;
                  let sp = line.slice(0, li).trim();
                  if (sp[0]=='*') sp = sp.slice(1).trim();
                  if (sp == '--') return;
                  aps.push(sp);
              });
              ac(aps);
          });
      });
  }
docs: Scan WiFi network
  @return {Promise} Return list of access points