code: def get_service_definition(self, service_type, identifier, allow_fault_in=None, preview_fault_in=None):
          
          route_values = {}
          if service_type is not None:
              route_values['serviceType'] = self._serialize.url('service_type', service_type, 'str')
          if identifier is not None:
              route_values['identifier'] = self._serialize.url('identifier', identifier, 'str')
          query_parameters = {}
          if allow_fault_in is not None:
              query_parameters['allowFaultIn'] = self._serialize.query('allow_fault_in', allow_fault_in, 'bool')
          if preview_fault_in is not None:
              query_parameters['previewFaultIn'] = self._serialize.query('preview_fault_in', preview_fault_in, 'bool')
          response = self._send(http_method='GET',
                                location_id='d810a47d-f4f4-4a62-a03f-fa1860585c4c',
                                version='5.0-preview.1',
                                route_values=route_values,
                                query_parameters=query_parameters)
          return self._deserialize('ServiceDefinition', response)
docs: GetServiceDefinition.
          [Preview API] Finds a given service definition.
          :param str service_type:
          :param str identifier:
          :param bool allow_fault_in: If true, we will attempt to fault in a host instance mapping if in SPS.
          :param bool preview_fault_in: If true, we will calculate and return a host instance mapping, but not persist it.
          :rtype: :class:`<ServiceDefinition> <azure.devops.v5_0.location.models.ServiceDefinition>`