code: def get_service_definitions(self, service_type=None):
          
          route_values = {}
          if service_type is not None:
              route_values['serviceType'] = self._serialize.url('service_type', service_type, 'str')
          response = self._send(http_method='GET',
                                location_id='d810a47d-f4f4-4a62-a03f-fa1860585c4c',
                                version='5.0-preview.1',
                                route_values=route_values)
          return self._deserialize('[ServiceDefinition]', self._unwrap_collection(response))
docs: GetServiceDefinitions.
          [Preview API]
          :param str service_type:
          :rtype: [ServiceDefinition]