code: def copy_structure(
      src_fs,  # type: Union[FS, Text]
      dst_fs,  # type: Union[FS, Text]
      walker=None,  # type: Optional[Walker]
  ):
      # type: (...) -> None
      
      walker = walker or Walker()
      with manage_fs(src_fs) as _src_fs:
          with manage_fs(dst_fs, create=True) as _dst_fs:
              with _src_fs.lock(), _dst_fs.lock():
                  for dir_path in walker.dirs(_src_fs):
                      _dst_fs.makedir(dir_path, recreate=True)
docs: Copy directories (but not files) from ``src_fs`` to ``dst_fs``.
  
      Arguments:
          src_fs (FS or str): Source filesystem (instance or URL).
          dst_fs (FS or str): Destination filesystem (instance or URL).
          walker (~fs.walk.Walker, optional): A walker object that will be
              used to scan for files in ``src_fs``. Set this if you only
              want to consider a sub-set of the resources in ``src_fs``.