code: def ensure_readable(self):
          
          self.ensure_exists()
          if not self.context.is_readable(self.directory):
              if self.context.have_superuser_privileges:
                  msg = "The directory %s isn't readable!"
                  raise ValueError(msg % self)
              else:
                  raise ValueError(compact("""
                      The directory {location} isn't readable, most likely
                      because of permissions. Consider using the --use-sudo
                      option.
                  """, location=self))
docs: Make sure the location exists and is readable.