docs: def github_belspec_files(spec_dir, force: bool = False):
      """Get belspec files from Github repo
  
  
      Args:
          spec_dir: directory to store the BEL Specification and derived files
          force: force update of BEL Specifications from Github - skipped if local files less than 1 day old
      """
  
      if not force:
          dtnow = datetime.datetime.utcnow()
          delta = datetime.timedelta(1)
          yesterday = dtnow - delta
  
          for fn in glob.glob(f"{spec_dir}/bel*yaml"):
              if datetime.datetime.fromtimestamp(os.path.getmtime(fn)) > yesterday:
                  log.info("Skipping BEL Specification update - specs less than 1 day old")
                  return
  
      repo_url = "https://api.github.com/repos/belbio/bel_specifications/contents/specifications"
      params = {}
      github_access_token = os.getenv("GITHUB_ACCESS_TOKEN", "")
      if github_access_token:
          params = {"access_token": github_access_token}
  
      r = requests.get(repo_url, params=params)
      if r.status_code == 200:
          results = r.json()
          for f in results:
              url = f["download_url"]
              fn = os.path.basename(url)
  
              if "yaml" not in fn and "yml" in fn:
                  fn = fn.replace("yml", "yaml")
  
              r = requests.get(url, params=params, allow_redirects=True)
              if r.status_code == 200:
                  open(f"{spec_dir}/{fn}", "wb").write(r.content)
              else:
                  sys.exit(
                      f"Could not get BEL Spec file {url} from Github -- Status: {r.status_code}  Msg: {r.content}"
                  )
      else:
          sys.exit(
              f"Could not get BEL Spec directory listing from Github -- Status: {r.status_code}  Msg: {r.content}"
          )