docs: def set_long_features(self, features, columns_to_set=[], partition=2):
          """ Sets features of double the duration
  
          Example: Setting 14 day RSIs to longer will create add a
              feature column of a 28 day RSIs.
  
          Args:
              features: Pandas DataFrame instance with columns as numpy.float32 features.
              columns_to_set: List of strings of feature names to make longer
              partition: Int of how many dates to take into consideration
                  when evaluating technical analysis indicators.
  
          Returns:
              Pandas DataFrame instance with columns as numpy.float32 features.
          """
          # Create long features DataFrame
          features_long = self.set_features(partition=2 * partition)
  
          # Remove features not specified by args.long
          unwanted_features = [f for f in features.columns if f not in columns_to_set]
          features_long = features_long.drop(unwanted_features, axis=1)
  
          # Prefix long columns with 'long_' to fix naming conflicts
          features_long.columns = ['long_{0}'.format(f) for f in features_long.columns]
  
          # Merge the two DataFrames
          skip = partition
          return pd.concat([features[skip:].reset_index(drop=True),
                           features_long],
                           axis=1)