code: def _fetch_surf_fsaverage(dataset_name, data_dir=None):
      """Ship fsaverage{3,4,6,7} meshes.
  
      These meshes can be used for visualization purposes, but also to run
      cortical surface-based searchlight decoding.
  
      The source of the data is downloaded from OSF.
      """
      dataset_dir = get_dataset_dir(dataset_name, data_dir=data_dir)
      opts = {"uncompress": True}
  
      url = {
          "fsaverage3": "https://osf.io/azhdf/download",
          "fsaverage4": "https://osf.io/28uma/download",
          "fsaverage6": "https://osf.io/jzxyr/download",
          "fsaverage": "https://osf.io/svf8k/download",  # fsaverage7
      }[dataset_name]
  
      # List of attributes exposed by the dataset
      dataset_attributes = [
          f"{part}_{hemi}"
          for part in [
              "area",
              "curv",
              "flat",
              "infl",
              "pial",
              "sphere",
              "sulc",
              "thick",
              "white",
          ]
          for hemi in ["left", "right"]
      ]
  
      # Note that the file names match the attribute's
      fetch_files(
          dataset_dir,
          [
              (f"{attribute}.gii.gz", url, opts)
              for attribute in dataset_attributes
          ],
      )
  
      result = {
          attribute: os.path.join(dataset_dir, f"{attribute}.gii.gz")
          for attribute in dataset_attributes
      }
      result["description"] = str(get_dataset_descr(dataset_name))
  
      return Bunch(**result)
  
imports: import functools
  import os
  import warnings
  from pathlib import Path
  import numpy
  import pandas
  from scipy.ndimage import binary_closing
  from sklearn.utils import Bunch
  from .._utils import check_niimg, fill_doc
  from ..image import get_data, new_img_like, resampling
  from ._utils import fetch_files, get_dataset_descr, get_dataset_dir
label_desc: Use image node_id 13 for calling a global function with example usage: _fetch_surf_fsaverage(dataset_name, data_dir) and returns: Bunch