class_docstr: Container object for the variables defined in a config file.
  
  `VariableSet` can be used as a plain dictionary, with the variable names
  as keys.
  
  Parameters
  ----------
  d : dict
      Dict of items in the "variables" section of the configuration file.
code: def __getitem__(self, name):
      return self._raw_data[name]
  
imports: from __future__ import division, absolute_import, print_function
  import sys
  import re
  import os
label_desc: Use image node_id 6 for calling the VariableSet obj's underlying member method code with example usage: obj.__getitem__(name) and returns: self