code: def impute():
      # Connect to a pre-existing cluster
  
      prostate = h2o.upload_file(
          pyunit_utils.locate("smalldata/logreg/prostate_missing.csv")
      )
      prostate.dim
  
      # print "Summary of the data in iris_missing.csv"
      # print "Each column has 50 missing observations (at random)"
      # prostate.summary()
  
      # print "Make a copy of the original dataset to play with."
  
      print("Impute a numeric column with the mean")
      nas = prostate["DPROS"].isna().sum()
      print("NAs before imputation: {0}".format(nas))
      prostate.impute("DPROS", method="mean")
  
      nas = prostate["DPROS"].isna().sum()
      print("NAs after imputation: {0}".format(nas))
  
      # OTHER POSSIBLE SYNTAXES ALLOWED:
      prostate = h2o.upload_file(
          pyunit_utils.locate("smalldata/logreg/prostate_missing.csv")
      )
      prostate.impute(8, method="mean")
  
      prostate = h2o.upload_file(
          pyunit_utils.locate("smalldata/logreg/prostate_missing.csv")
      )
      prostate.impute("VOL", method="mean")
  
      # USING  MEDIAN
      print("Impute a numeric column with the median")
  
      prostate = h2o.upload_file(
          pyunit_utils.locate("smalldata/logreg/prostate_missing.csv")
      )
      prostate.impute("VOL", method="median")
  
      prostate = h2o.upload_file(
          pyunit_utils.locate("smalldata/logreg/prostate_missing.csv")
      )
      prostate.impute(8, method="median")
  
      prostate = h2o.upload_file(
          pyunit_utils.locate("smalldata/logreg/prostate_missing.csv")
      )
      prostate.impute("VOL", method="median")
  
label_desc: Use image node_id 1 for calling a global function with example usage: impute() without return types