class_docstr: Simple Dataset wrapper for lists and arrays.
  
  Parameters
  ----------
  data : dataset-like object
      Any object that implements `len()` and `[]`.
code: def __len__(self):
      return len(self._data)
  
imports: import os
  from ...None import recordio, ndarray
  from ...util import default_array
label_desc: Use image node_id 2 for calling the SimpleDataset obj's underlying member method code with example usage: obj.__len__() and returns: len