code: def h2o_H2OFrame_levels():
      """
      Python API test: h2o.frame.H2OFrame.levels()
      """
      python_lists = np.random.randint(-2, 2, (10000, 2))
      h2oframe = h2o.H2OFrame(
          python_obj=python_lists, column_types=["enum", "enum"]
      )
      clist = h2oframe.levels()
  
      assert_is_type(clist, list)  # check return type
      assert (
          len(clist) == 2
      ), "h2o.H2OFrame.levels() command is not working."
  
imports: import sys
  import h2o
  from tests import pyunit_utils
  from h2o.utils.typechecks import assert_is_type
  from random import randrange
  import numpy
label_desc: Use image node_id 1 for calling a global function with example usage: h2o_H2OFrame_levels() without return types