code: def unpack_scalar(cls, dataset, data):
          
          if len(data) != 1:
              return data
          key = list(data.keys())[0]
  
          if len(data[key]) == 1 and key in dataset.vdims:
              scalar = data[key][0]
              return scalar.compute() if hasattr(scalar, 'compute') else scalar
          return data
docs: Given a dataset object and data in the appropriate format for
          the interface, return a simple scalar.