class_docstr: Class for the  backend.
  
  Parameter
  ---------
  data : array-like or string or None
      Indicates the backend to choose.
      If data is a Numpy array or data equals 'numpy' or data is None,
      self.backend is set to NumpyBackend().
      If data is a PyTorch array or data equals 'pytorch',
      self.backend is set to PytorchBackend().
      Optional, default equals None.
code: def set_backend(self, data=None):
      self.backend = select_backend(data)
  
file_path: tslearn/tslearn/backend/backend.py
imports: from tslearn.backend.numpy_backend import NumPyBackend
label_desc: Use image node_id 3 for calling the Backend obj's underlying member method code with example usage: obj.set_backend(data) without return types