code: def get_cert_builder(expires):
      
      now = datetime.utcnow().replace(second=0, microsecond=0)
  
      if expires is None:
          expires = get_expires(expires, now=now)
      expires = expires.replace(second=0, microsecond=0)
  
      builder = x509.CertificateBuilder()
      builder = builder.not_valid_before(now)
      builder = builder.not_valid_after(expires)
      builder = builder.serial_number(x509.random_serial_number())
  
      return builder
docs: Get a basic X509 cert builder object.
  
      Parameters
      ----------
  
      expires : datetime
          When this certificate will expire.