class_docstr: DataLoaderTransformers are used to transform the output of a DataLoader.
  DataLoader doesn't have easy access to the device or graph, so any
  computation that should happen there should use a DataLoaderTransformer.
code: def transform(self, t):
      raise NotImplemented()
  
imports: from __future__ import division
  import numpy
  from neon import NervanaObject
label_desc: Use image node_id 4 for calling the DataLoaderTransformer obj's underlying member method code with example usage: obj.transform(t) without return types