code: def create_access_token(self, authorization_request, subject_identifier, scope=None):
          # type: (oic.oic.message.AuthorizationRequest, str, Optional[List[str]]) -> se_leg_op.access_token.AccessToken
          
          if not self._is_valid_subject_identifier(subject_identifier):
              raise InvalidSubjectIdentifier('{} unknown'.format(subject_identifier))
  
          scope = scope or authorization_request['scope']
  
          return self._create_access_token(subject_identifier, authorization_request.to_dict(), ' '.join(scope))
docs: Creates an access token bound to the authentication request and the authenticated user identified by the
          subject identifier.