code: def group_by():
      """
      This test checks that if a groupby operation is specified for frames with string columns, a warning is
      generated about the string columns being skipped.
  
      In addition, it checks that operations on numeric/enum columns are performed and generated the correct
      expected outputs.
  
      """
      # Connect to a pre-existing cluster
  
      buffer = StringIO()  # redirect output
      sys.stderr = buffer
      h2o_f1 = h2o.import_file(
          path=pyunit_utils.locate(
              "smalldata/jira/test_groupby_with_strings.csv"
          ),
          col_types=["real", "string", "string", "real"],
      )
      grouped = h2o_f1.group_by("C1")
      grouped.mean(na="all").median(na="all").max(na="all").min(
          na="all"
      ).sum(na="all")
      print(grouped.get_frame())
      print("Checking number of warning messages...")
      check_warnings(2, buffer)
  
imports: import sys
  import h2o
  from tests import pyunit_utils
label_desc: Use image node_id 1 for calling a global function with example usage: group_by() without return types