def open_dataset(self, service):
if not self.dataset:<EOL><INDENT>path = os.path.join(SERVICE_DATA_ROOT, service.data_path)<EOL>self.dataset = netCDF4.Dataset(path, '<STR_LIT:r>')<EOL><DEDENT>return self.dataset<EOL>
Opens and returns the NetCDF dataset associated with a service, or returns a previously-opened dataset