code: def on_cols_multi():
      return ["Origin", "Destination", "Period"]
  
imports: import numpy
  import pytest
  import pandas.util._test_decorators
  import pandas
  from pandas import DataFrame, Index, MultiIndex, RangeIndex, Series, Timestamp, option_context
  import pandas._testing
  from pandas.core.reshape.concat import concat
  from pandas.core.reshape.merge import merge
label_desc: Use image node_id 5 for calling a global function with example usage: on_cols_multi() and returns: list