code: def copy_fs(
      src_fs,  # type: Union[FS, Text]
      dst_fs,  # type: Union[FS, Text]
      walker=None,  # type: Optional[Walker]
      on_copy=None,  # type: Optional[_OnCopy]
      workers=0,  # type: int
  ):
      # type: (...) -> None
      
      return copy_dir(
          src_fs, "/", dst_fs, "/", walker=walker, on_copy=on_copy, workers=workers
      )
docs: Copy the contents of one filesystem to another.
  
      Arguments:
          src_fs (FS or str): Source filesystem (URL or instance).
          dst_fs (FS or str): Destination filesystem (URL or instance).
          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``.
          on_copy (callable): A function callback called after a single file copy
              is executed. Expected signature is ``(src_fs, src_path, dst_fs,
              dst_path)``.
          workers (int): Use `worker` threads to copy data, or ``0`` (default) for
              a single-threaded copy.