code: function _commonOptsDefine(opts){
    let {C, O , days, bit} = opts;
    C = C || 'CN';
    O = O || 'AAA ssl-self-signed';
    let OU = O + ' ' + Date.now();
    days = days || 365* 100;
    bit = bit || 2048;
    return {C, O, OU, days, bit};
  }
docs: //if not have openssl, the program will stop in next line; try { execSync('openssl version'); }catch(e){ throw new Error('ssl-self-signed need openssl'); }