code: def h2oassembly_download_mojo_col_op_string_unary():
      test_unary_string_function(H2OFrame.lstrip, set="+&")
      test_unary_string_function(H2OFrame.rstrip, set="+&")
      test_unary_string_function(
          H2OFrame.gsub,
          pattern="tt",
          replacement="bbcc",
          ignore_case=True,
      )
      test_unary_string_function(
          H2OFrame.sub,
          pattern="tt",
          replacement="bbcc",
          ignore_case=True,
      )
      test_unary_string_function(
          H2OFrame.substring, start_index=2, end_index=8
      )
      test_unary_string_function(H2OFrame.tolower)
      test_unary_string_function(H2OFrame.toupper)
      test_unary_string_function(H2OFrame.trim)
  
imports: import sys, os
  from tests import pyunit_utils
  from h2o.assembly import *
  from h2o.transforms.preprocessing import *
  from h2o.pipeline import H2OMojoPipeline
label_desc: Use image node_id 1 for calling a global function with example usage: h2oassembly_download_mojo_col_op_string_unary() without return types