def get_service_definition(self, service_type, identifier, allow_fault_in=None, preview_fault_in=None):
        """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>`
        """
        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)
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>`