class_docstr: This class functions as a configuration set for headless runs.
  The default config class is wx-based, which means we have to replace it
  here with this psuedo-replacement that has the same interface
code: def Exists(self, kwd):
      return kwd in self.__preferences
  
file_path: CellProfiler/src/subpackages/core/cellprofiler_core/preferences/_headless_configuration.py
imports: import json
label_desc: Use image node_id 6 for calling the HeadlessConfiguration obj's underlying member method code with example usage: obj.Exists(kwd) and returns: unknown