code: def h2o_H2OFrame_flatten():
      """
      Python API test: h2o.frame.H2OFrame.flatten()
  
      copied from pyunit_entropy.py
      """
      frame = h2o.H2OFrame.from_python(["redrum"])
      g = frame.flatten()
      assert (
          g == "redrum"
      ), "h2o.H2OFrame.flatten() command is not working."
  
label_desc: Use image node_id 1 for calling a global function with example usage: h2o_H2OFrame_flatten() without return types