code: def from_git_rev_read(path):
      
      if ":" not in path:
          raise ValueError("Path identifier must start with a revision hash.")
  
      cmd = "git", "show", "-t", path
      try:
          return subprocess.check_output(cmd).rstrip().decode("utf-8")
      except subprocess.CalledProcessError:
          raise ValueError
docs: Retrieve given file path contents of certain Git revision.