class_docstr: :class:`~fastNLP.core.dataset.DatSet` 中用于表示列的数据类型。
  
  :param name: 字符串的名称
  :param content: 任意类型的数据
class_docstr_tok: [":","class",":","`","~fastNLP.core.dataset.DatSet","`","\u4e2d\u7528\u4e8e\u8868\u793a\u5217\u7684\u6570\u636e\u7c7b\u578b\u3002",":","param","name",":","\u5b57\u7b26\u4e32\u7684\u540d\u79f0",":","param","content",":","\u4efb\u610f\u7c7b\u578b\u7684\u6570\u636e"]
code: def __iter__(self):
      for idx in range(len(self)):
          yield self[idx]
  
imports: from collections import Counter
  from typing import Any, Union, List, Callable
  from ..log import logger
  import numpy
label_desc: Use image node_id 4 for calling the FieldArray obj's underlying member method code with example usage: obj.__iter__() without return types