Added ValueError and working example

  Examples

  --------

  >>> import deepchem as dc

  >>> tasks, datasets, transformers = dc.molnet.load_mydataset()

  >>> tasks, datasets, transformers = dc.molnet.load_tox21(reload=False)

  >>> train_dataset, val_dataset, test_dataset = datasets

  >>> n_tasks = len(tasks)

  >>> n_features = train_dataset.get_data_shape()[0]

  >>> model = dc.models.MultiTaskClassifier(n_tasks, n_features)

  >>> model = dc.models.MultitaskClassifier(n_tasks, n_features)

  """

  # Warning message about this template

  raise ValueError("""

    This is a template function and it doesn't do anything!

    Use this function as a reference when implementing new

    loaders for MoleculeNet datasets.

    """)

  # Featurize mydataset

  logger.info("About to featurize mydataset.")

  my_tasks = ["task1", "task2", "task3"]  # machine learning targets