code: def _build_backend_map():
      """
      The set of supported backends is defined here.
      """
      backends = defaultdict(lambda: None)
  
      if torch_installed():
          import torch
  
          backends[torch.__name__] = torch.__name__
          backends[
              "py" + torch.__name__
          ] = torch.__name__  # For compatibility with earlier versions.
  
          backends[torch.jit.__name__] = torch.jit.__name__
          backends[
              "torchscript"
          ] = torch.jit.__name__  # For reference outside Hummingbird.
  
      if onnx_runtime_installed():
          import onnx
  
          backends[onnx.__name__] = onnx.__name__
  
      if tvm_installed():
          import tvm
  
          backends[tvm.__name__] = tvm.__name__
  
      return backends
  
file_path: hummingbird/hummingbird/ml/supported.py
imports: from collections import defaultdict
  from .exceptions import MissingConverter
  from ._utils import torch_installed, sklearn_installed, lightgbm_installed, xgboost_installed, onnx_runtime_installed, tvm_installed, sparkml_installed, prophet_installed
label_desc: Use image node_id 7 for calling a global function with example usage: _build_backend_map() and returns: backends