def __init__(self, base_fd, pathspec=None, progress_callback=None,
               full_pathspec=None):
    _ = pathspec
    _ = full_pathspec
    self.base_fd = base_fd
    self.progress_callback = progress_callback
    if base_fd is None:
      self.pathspec = rdf_paths.PathSpec()
    else:
      # Make a copy of the base pathspec.
      self.pathspec = base_fd.pathspec.Copy()
    self.metadata = {}
Constructor.
dataset/ETHPy150Open google/grr/grr/client/vfs.py/VFSHandler.__init__