code: def get_defaults(module_name: Optional[str] = None) -> Dict[str, Any]:
      """Get featurizers, transformers, and splitters.
  
      This function returns a dictionary with class names as keys and classes
      as values. All MolNet ``load_x`` functions should specify which
      featurizers, transformers, and splitters the dataset supports and
      provide sensible defaults.
  
      Parameters
      ----------
      module_name : {"feat", "trans", "splits"}
          Default classes from deepchem.`module_name` will be returned.
  
      Returns
      -------
      defaults : Dict[str, Any]
          Keys are class names and values are class constructors.
  
      Examples
      --------
      >> splitter = get_defaults('splits')['RandomSplitter']()
      >> transformer = get_defaults('trans')['BalancingTransformer'](dataset, {"transform_X": True})
      >> featurizer = get_defaults('feat')["CoulombMatrix"](max_atoms=5)
  
      """
  
      if module_name not in ["feat", "trans", "splits"]:
          raise ValueError(
              "Input argument must be either 'feat', 'trans', or 'splits'."
          )
  
      if module_name == "feat":
          sc: Any = Featurizer
      elif module_name == "trans":
          sc = Transformer
      elif module_name == "splits":
          sc = Splitter
  
      module_name = "deepchem." + module_name
  
      module = importlib.import_module(module_name, package="deepchem")
  
      defaults = {
          x[0]: x[1]
          for x in inspect.getmembers(module, inspect.isclass)
          if issubclass(x[1], sc)
      }
  
      return defaults
  
file_path: deepchem/deepchem/molnet/defaults.py
imports: import importlib
  import inspect
  import logging
  from typing import Optional, Dict, Any
  from deepchem.feat.base_classes import Featurizer
  from deepchem.trans.transformers import Transformer
  from deepchem.splits.splitters import Splitter
label_desc: Use image node_id 1 for calling a global function with example usage: get_defaults(module_name) and returns: defaults