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 _init_parse(self):
      for k, v in self._raw_data.items():
          self._init_parse_var(k, v)
  
imports: from __future__ import division, absolute_import, print_function
  import sys
  import re
  import os
label_desc: Use image node_id 2 for calling the VariableSet obj's underlying member method code with example usage: obj._init_parse() without return types