code: def get_authority_key_identifier(self):
          
  
          try:
              ski = self.x509.extensions.get_extension_for_class(x509.SubjectKeyIdentifier)
          except x509.ExtensionNotFound:
              return x509.AuthorityKeyIdentifier.from_issuer_public_key(self.x509.public_key())
          else:
              return x509.AuthorityKeyIdentifier.from_issuer_subject_key_identifier(ski)
docs: Return the AuthorityKeyIdentifier extension used in certificates signed by this CA.