code: def validate_sha(sha):
      
      cmd = ["git", "log", "-r", sha]
      try:
          subprocess.check_output(cmd, stderr=subprocess.STDOUT)
      except subprocess.SubprocessError:
          raise ValueError(
              f"The sha listed in the branch name, {sha}, is not present in the repository"
          )
docs: Validate that a hexdigest sha is a valid commit in the repo
  
      raises ValueError if the sha does not reference a commit within the repo