docs: def _certificate_required(cls, hostname, port=XCLI_DEFAULT_PORT,
                                ca_certs=None, validate=None):
          '''
          returns true if connection should verify certificate
          '''
          if not ca_certs:
              return False
  
          xlog.debug("CONNECT SSL %s:%s, cert_file=%s",
                     hostname, port, ca_certs)
          certificate = ssl.get_server_certificate((hostname, port),
                                                   ca_certs=None)
          # handle XIV pre-defined certifications
          # if a validation function was given - we let the user check
          # the certificate himself, with the user's own validate function.
          # if the validate returned True - the user checked the cert
          # and we don't need check it, so we return false.
          if validate:
              return not validate(certificate)
          return True