join_tables: Specify left/right columns to merge on -> multiple columns with sam...

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https://api.github.com/fairtracks/omnipy_examples/blob/b02fdf052f6ee97a3623c02d47d492b91e3bfc67/tests/test_dataframe_merge.py#L220

#     }

# Further tests
# TODO: join_tables: When Multiple columns that have the same name -> check consistency of common columns.
#       If identical, then merge columns.
# TODO: join_tables: Specify left/right columns to merge on
# TODO: join_tables: Specify left/right columns to merge on -> multiple columns with same name
# TODO: join_tables: Specify left/right columns to merge on -> specified columns do not exist
# TODO: join_tables: No overlapping column names in A and B
# TODO: join_tables: Empty dataframe
# TODO: join_tables: Multiple matching rows
# TODO: join_tables: Multiple tables