code: def from_df(cls, df:DataFrame, path:PathOrStr, cols:IntsOrStrs=0, folder:PathOrStr=None, suffix:str='', **kwargs)->'ItemList':
          "Get the filenames in `cols` of `df` with `folder` in front of them, `suffix` at the end."
          suffix = suffix or ''
          res = super().from_df(df, path=path, cols=cols, **kwargs)
          pref = f'{res.path}{os.path.sep}'
          if folder is not None: pref += f'{folder}{os.path.sep}'
          res.items = np.char.add(np.char.add(pref, res.items.astype(str)), suffix)
          return ref from_df(cls, df:DataFrame, path:PathOrStr, cols:IntsOrStrs=0, folder:PathOrStr=None, suffix:str='', **kwargs)->'ItemList':
          "Get the filenames in `cols` of `df` with `folder` in front of them, `suffix` at the end."
          suffix = suffix or ''
          res = super().from_df(df, path=path, cols=cols, **kwargs)
          pref = f'{res.path}{os.path.sep}'
          if folder is not None: pref += f'{folder}{os.path.sep}'
          res.items = np.char.add(np.char.add(pref, res.items.astype(str)), suffix)
          return res
docs: Get the filenames in `cols` of `df` with `folder` in front of them, `suffix` at the end.