docs: def clear_autoflow(cls, obj, name=None):
          """
          Clear autoflow's tensor storage.
  
          :param obj: target GPflow object.
          :param name: accepts either string value which is unique part of
              an internal attribute name or None value. When None value is passed all
              storages will be cleared, in other words it clears everything with common
              autoflow prefix.
  
          :raises: ValueError exception if `name` is not a string.
          """
          if name is not None and not isinstance(name, str):
              raise ValueError('Name must be a string.')
          prefix = cls.__autoflow_prefix__
          if name:
              prefix = "" if name.startswith(prefix) else prefix
              delattr(obj, prefix + name)
          else:
              keys = [attr for attr in obj.__dict__ if attr.startswith(prefix)]
              for key in keys:
                  delattr(obj, key)