code: def get_diff(repo: "git.Repo", commit_ref: str) -> Optional[str]:
      try:
          from git.exc import GitCommandError
  
          try:
              diff = repo.git.diff(commit_ref, index=False)
  
              # add a newline at the end (required to be a valid `patch` file)
              if diff and diff[-1] != "\n":
                  diff += "\n"
              return diff
          except GitCommandError:
              return
      except ImportError:
          return None
  
file_path: neptune-client/src/neptune/internal/utils/git.py
imports: import logging
  import warnings
  from dataclasses import dataclass
  from datetime import datetime
  from typing import TYPE_CHECKING, List, Optional, Union
  from neptune.attributes.constants import DIFF_HEAD_INDEX_PATH, UPSTREAM_INDEX_DIFF
  from neptune.types import File
  from neptune.types.atoms.git_ref import GitRef, GitRefDisabled
label_desc: Use image node_id 4 for calling a global function with example usage: get_diff(repo, commit_ref) and returns: diff, None