code: def test_md5_string():
      assert hashutil.md5_string("") == "1B2M2Y8AsgTpgAmY7PhCfg=="
      assert hashutil.md5_string("foo") == "rL0Y20zC+Fzt72VPzMSk2A=="
  
file_path: wandb/tests/pytest_tests/unit_tests/test_lib/test_hashutil.py
imports: import base64
  import hashlib
  from hypothesis import given
  from hypothesis import strategies
  from wandb.sdk.lib import hashutil
label_desc: Use image node_id 1 for calling a global function with example usage: test_md5_string() without return types