code: def test_version(tmpdir):
      """Verify versions of loggers are concatenated properly."""
      logger1 = CSVLogger(tmpdir, version=0)
      logger2 = CSVLogger(tmpdir, version=2)
      logger3 = CSVLogger(tmpdir, version=1)
      logger4 = CSVLogger(tmpdir, version=0)
      loggers = [logger1, logger2, logger3, logger4]
      version = _version([])
      assert version == ""
      version = _version([logger3])
      assert version == 1
      version = _version(loggers)
      assert version == "0_2_1"
      version = _version(loggers, "-")
      assert version == "0-2-1"
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_version(tmpdir) without return types