code: def delete_blob(self, blob_name: str) -> None:
      global _MOCK_BUCKET_CONTENT
      del _MOCK_BUCKET_CONTENT[blob_name]
  
imports: from __future__ import annotations
  import contextlib
  import io
  import os
  from typing import Dict
  from typing import Optional
  from typing import TYPE_CHECKING
  from unittest.mock import patch
  import google.cloud.storage
  import pytest
  from optuna.artifacts import GCSArtifactStore
  from optuna.artifacts.exceptions import ArtifactNotFound
label_desc: Use image node_id 3 for calling the MockBucket obj's underlying member method code with example usage: obj.delete_blob(blob_name) without return types