code: def _find_substitutions(cls, item):
          
          if isinstance(item, ConfigValues):
              return item.get_substitutions()
  
          substitutions = []
          elements = []
          if isinstance(item, ConfigTree):
              elements = item.values()
          elif isinstance(item, list):
              elements = item
  
          for child in elements:
              substitutions += cls._find_substitutions(child)
          return substitutions
docs: Convert HOCON input into a JSON output
  
          :return: JSON string representation
          :type return: basestring