code: def gen_ca_cert(filename, dirname, days, silent=False):
      
      keyfile = os.path.join(dirname, '{}.key'.format(filename))
      ca_crt = os.path.join(dirname, '{}.crt'.format(filename))
      gen_private_key(keyfile, silent)
      gen_self_signed_cert(ca_crt, keyfile, days, silent)
docs: generate a CA key and certificate key pair.
      :param filename: prefix for the key and cert file
      :param dirname: name of the directory
      :param days: days of the certificate being valid
      :param silent: whether to suppress output