code: def _filter(self, filename: str, df: pd.DataFrame) -> pd.DataFrame:
          
          view = self._view.get(filename)
          if view is None:
              return df
  
          for col, values in view.items():
              # If applicable, filter this dataframe by the given set of values
              if col in df.columns:
                  df = df[df[col].isin(setwrap(values))]
  
          return df
docs: Apply view filters