code: def __len__(self) -> int:
      if not self._columns:
          return 0
      return len(self.columns[0])
  
imports: from collections import abc
  from itertools import chain, repeat, zip_longest
  from operator import itemgetter
  from typing import TYPE_CHECKING, Any, Dict, ItemsView, Iterable, Iterator, List, Mapping, MutableSequence, Optional, Sequence, Set, Tuple, Union, overload
  from funcy import reraise
label_desc: Use image node_id 20 for calling the TabularData obj's underlying member method code with example usage: obj.__len__() and returns: len, int