fix tasks, transformers

import deepchem

import numpy as np

from deepchem.data import Dataset

from deepchem.molnet.load_function.molnet_loader import _MolnetLoader

from deepchem.molnet.load_function.molnet_loader import TransformerGenerator, _MolnetLoader

from typing import List, Optional, Tuple, Union

import deepchem as dc

USPTO_50K_URL = "https://deepchemdata.s3.us-west-1.amazonaws.com/datasets/USPTO_50K.csv"

USPTO_FULL_URL = "https://deepchemdata.s3.us-west-1.amazonaws.com/datasets/USPTO_FULL.csv"

USPTO_TASK = []

class _USPTOLoader(_MolnetLoader):

    if self.subset == 'FULL':

      dataset_url = USPTO_FULL_URL

      if self.splitter == 'SpecifiedSplitter':

        raise ValueError("There is no pre computed split for the full dataset, use a custom split instead!")

    dataset_file = os.path.join(self.data_dir, self.name + '.csv')

      dc.utils.data_utils.download_url(url=dataset_url, dest_dir=self.data_dir)

      logger.info("Dataset download complete.")

    loader = dc.data.CSVLoader(tasks=[], featurizer=self.featurizer)

    loader = dc.data.CSVLoader(tasks=self.tasks, featurizer=self.featurizer)

    return loader.create_dataset(dataset_file, shard_size=8192)

def load_uspto(

    featurizer=None,  # should I remove this?

    featurizer: Union[dc.feat.Featurizer, str] = dc.feat.UserDefinedFeaturizer([]),  # This will be changed to dummy featurizer!

    splitter: Union[dc.splits.Splitter, str, None] = 'SpecifiedSplitter',

    transformers=None,

    transformers: List[Union[TransformerGenerator, str]] = [],

    reload: bool = True,

    data_dir: Optional[str] = None,

    save_dir: Optional[str] = None,

  subset : str (default 'MIT')

    Subset of dataset to download. 'FULL', 'MIT', 'STEREO', and '50K' are supported.

  sep_reagent : bool (default True)

    Toggle to load dataset with reactants and reagents separated or mixed.

    Toggle to load dataset with reactants and reado I call it 

  Returns

  -------

  tasks, datasets, transformers : tuple

  # get test and valid lists if subset is MIT, 50K, STEREO and splitter = specified.

  # if subset is Full use splitter passed by the user.

  # splitter = dc.splits.SpecifiedSplitter(valid_indices=,test_indices=)

  featurizer = dc.feat.UserDefinedFeaturizer([])

  loader = _USPTOLoader(

      featurizer,

      splitter,

      transformers,

      USPTO_TASK,

      data_dir,

      save_dir,

      subset=subset,