code: def header():
      path = "smalldata/jira/hexdev_29.csv"
  
      fhex_header_true = h2o.import_file(
          pyunit_utils.locate(path), header=1
      )
  
      fhex_header_unknown = h2o.import_file(
          pyunit_utils.locate(path), header=0
      )
  
      fhex_header_false = h2o.import_file(
          pyunit_utils.locate(path), header=-1
      )
  
      fhex_header_unspecified = h2o.import_file(
          pyunit_utils.locate(path)
      )
  
      try:
          h2o.import_file(pyunit_utils.locate(path), header=2)
          assert False
      except h2o.exceptions.H2OTypeError:
          pass
  
      assert fhex_header_true.nrow == fhex_header_false.nrow - 1
      assert fhex_header_unknown.nrow in {
          fhex_header_false.nrow,
          fhex_header_true.nrow,
      }
      assert fhex_header_unspecified.nrow in {
          fhex_header_false.nrow,
          fhex_header_true.nrow,
      }
  
label_desc: Use image node_id 1 for calling a global function with example usage: header() without return types