def _GetFailedRevisionFromCompileResult(compile_result):
  """Determines the failed revision given compile_result.

  Args:
    compile_result: A dict containing the results from a compile. Please refer
    to try_job_result_format.md for format check.

  Returns:
    The failed revision from compile_results, or None if not found.
  """
  return (
      compile_result.get('report', {}).get('culprit') if compile_result
      else None)