code: def test_register_converters_idempotent(spark):
      import glow.glow
  
      for _ in range(3):
          reload(glow.glow)
          one_d_converters = 0
          two_d_converters = 0
          for c in spark._sc._gateway._gateway_client.converters:
              if type(c) is OneDimensionalDoubleNumpyArrayConverter:
                  one_d_converters += 1
              if type(c) is TwoDimensionalDoubleNumpyArrayConverter:
                  two_d_converters += 1
          assert one_d_converters == 1
          assert two_d_converters == 1
  
file_path: glow/python/glow/tests/test_conversions.py
imports: from glow.conversions import OneDimensionalDoubleNumpyArrayConverter, TwoDimensionalDoubleNumpyArrayConverter
  from importlib import reload
  import numpy
  from py4j.protocol import Py4JJavaError
  from pyspark.ml.linalg import DenseMatrix
  from pyspark.sql.functions import lit
  from pyspark.sql.types import StringType
  import pytest
label_desc: Use image node_id 6 for calling a global function with example usage: test_register_converters_idempotent(spark) without return types