code: def _get_process_mapping():
      
      for impl in (proc, ps):
          try:
              mapping = impl.get_process_mapping()
          except EnvironmentError:
              continue
          return mapping
      raise ShellDetectionFailure('compatible proc fs or ps utility is required')
docs: Select a way to obtain process information from the system.
  
      * `/proc` is used if supported.
      * The system `ps` utility is used as a fallback option.