code: def test_memory_gb(self):
      assert gpu_spec("2GB") == {"memory": "2GB"}
  
imports: import argparse
  from typing import List, Tuple
  import pytest
  from dstack._internal.cli.services.configurators.profile import apply_profile_args, gpu_spec, register_profile_args
  from dstack._internal.core.models.profiles import Profile, ProfileGPU, ProfileResources, ProfileRetryPolicy, SpotPolicy
label_desc: Use image node_id 3 for calling the TestGPUSpec obj's underlying member method code with example usage: obj.test_memory_gb() without return types