intent: Merging two pandas dataframes
rewritten_intent: Create new DataFrame object by merging columns "key" of  dataframes `split_df` and `csv_df` and rename the columns from dataframes `split_df` and `csv_df` with suffix `_left` and `_right` respectively
snippet: pd.merge(split_df, csv_df, on=['key'], suffixes=('_left', '_right'))