code: def transform_frame(frame, transform, columns=None, direction='forward',
                      return_all=True, args=(), **kwargs):
      
      tfun, tname = parse_transform(transform, direction)
      columns = to_list(columns)
      if columns is None:
          columns = frame.columns
      if return_all:
          transformed = frame.copy()
          for c in columns:
              transformed[c] = tfun(frame[c], *args, **kwargs)
      else:
          transformed = frame.filter(columns).apply(tfun, *args, **kwargs)
      return transformed
docs: Apply transform to specified columns.
  
      direction: 'forward' | 'inverse'
      return_all: bool
          True -  return all columns, with specified ones transformed.
          False - return only specified columns.
  
      .. warning:: deprecated