code: def validate_dataset_string(self, dataset):
          
          if dataset:
              if '/' not in dataset:
                  raise ValueError('Dataset must be specified in the form of '
                                   '\'{username}/{dataset-slug}\'')
  
              split = dataset.split('/')
              if not split[0] or not split[1]:
                  raise ValueError('Invalid dataset specification ' + dataset)
docs: determine if a dataset string is valid, meaning it is in the format
              of {username}/{dataset-slug}.
               Parameters
              ==========
              dataset: the dataset name to validate