code: def _validate_options(cls, options):
          
          for opt1, opt2 in \
                  itertools.permutations(cls.BASE_ERROR_SELECTION_OPTIONS, 2):
              if getattr(options, opt1) and getattr(options, opt2):
                  log.error('Cannot pass both {} and {}. They are '
                            'mutually exclusive.'.format(opt1, opt2))
                  return False
  
          if options.convention and options.convention not in conventions:
              log.error("Illegal convention '{}'. Possible conventions: {}"
                        .format(options.convention,
                                ', '.join(conventions.keys())))
              return False
          return True
docs: Validate the mutually exclusive options.
  
          Return `True` iff only zero or one of `BASE_ERROR_SELECTION_OPTIONS`
          was selected.