code: def csvdiff_cmd(index_columns, from_csv, to_csv, style=None, output=None,
                  sep=',', quiet=False, ignore_columns=None, significance=None):
      
  
      if ignore_columns is not None:
          for i in ignore_columns:
              if i in index_columns:
                  error.abort("You can't ignore an index column")
  
      ostream = (open(output, 'w') if output
                 else io.StringIO() if quiet
                 else sys.stdout)
  
      try:
          if style == 'summary':
              _diff_and_summarize(from_csv, to_csv, index_columns, ostream,
                                  sep=sep, ignored_columns=ignore_columns,
                                  significance=significance)
          else:
              compact = (style == 'compact')
              _diff_files_to_stream(from_csv, to_csv, index_columns, ostream,
                                    compact=compact, sep=sep, ignored_columns=ignore_columns,
                                    significance=significance)
  
      except records.InvalidKeyError as e:
          error.abort(e.args[0])
  
      finally:
          ostream.close()
docs: Compare two csv files to see what rows differ between them. The files
      are each expected to have a header row, and for each row to be uniquely
      identified by one or more indexing columns.