class_docstr: 用于读取 **conll2003** 任务的 NER 数据。每一行有 4 列内容，空行意味着隔开两个句子。
  
  支持读取的内容如下::
  
      Nadim NNP B-NP B-PER
      Ladki NNP I-NP I-PER
  
      AL-AIN NNP B-NP B-LOC
      United NNP B-NP B-LOC
      Arab NNP I-NP I-LOC
      Emirates NNPS I-NP I-LOC
      1996-12-06 CD I-NP O
      ...
  
  读取的 :class:`~fastNLP.core.DataSet` 将具备以下的数据结构：
  
  .. csv-table:: 下面是 Conll2003Loader 加载后数据具备的结构, target 是 BIO2 编码
     :header: "raw_words", "target"
  
     "[Nadim, Ladki]", "[B-PER, I-PER]"
     "[AL-AIN, United, Arab, ...]", "[B-LOC, B-LOC, I-LOC, ...]"
     "[...]",  "[...]"
class_docstr_tok: ["\u7528\u4e8e\u8bfb\u53d6","*","*","conll2003","*","*","\u4efb\u52a1\u7684","NER","\u6570\u636e\u3002\u6bcf\u4e00\u884c\u6709","4","\u5217\u5185\u5bb9\uff0c\u7a7a\u884c\u610f\u5473\u7740\u9694\u5f00\u4e24\u4e2a\u53e5\u5b50\u3002","\u652f\u6301\u8bfb\u53d6\u7684\u5185\u5bb9\u5982\u4e0b",":",":","Nadim","NNP","B-NP","B-PER","Ladki","NNP","I-NP","I-PER","AL-AIN","NNP","B-NP","B-LOC","United","NNP","B-NP","B-LOC","Arab","NNP","I-NP","I-LOC","Emirates","NNPS","I-NP","I-LOC","1996-12-06","CD","I-NP","O","...","\u8bfb\u53d6\u7684",":","class",":","`","~fastNLP.core.DataSet","`","\u5c06\u5177\u5907\u4ee5\u4e0b\u7684\u6570\u636e\u7ed3\u6784\uff1a","..","csv-table",":",":","\u4e0b\u9762\u662f","Conll2003Loader","\u52a0\u8f7d\u540e\u6570\u636e\u5177\u5907\u7684\u7ed3\u6784",",","target","\u662f","BIO2","\u7f16\u7801",":","header",":","``","raw_words","''",",","``","target","''","``","[","Nadim",",","Ladki","]","''",",","``","[","B-PER",",","I-PER","]","''","``","[","AL-AIN",",","United",",","Arab",",","...","]","''",",","``","[","B-LOC",",","B-LOC",",","I-LOC",",","...","]","''","``","[","...","]","''",",","``","[","...","]","''"]
docstr: 传入的一个文件路径，将该文件读入DataSet中，field由ConllLoader初始化时指定的headers决定。
  
  :param str path: 文件的路径
  :return: DataSet
docstr_tok: ["\u4f20\u5165\u7684\u4e00\u4e2a\u6587\u4ef6\u8def\u5f84\uff0c\u5c06\u8be5\u6587\u4ef6\u8bfb\u5165DataSet\u4e2d\uff0cfield\u7531ConllLoader\u521d\u59cb\u5316\u65f6\u6307\u5b9a\u7684headers\u51b3\u5b9a\u3002",":","param","str","path",":","\u6587\u4ef6\u7684\u8def\u5f84",":","return",":","DataSet"]
code: def _load(self, path):
      r"""
      传入的一个文件路径，将该文件读入DataSet中，field由ConllLoader初始化时指定的headers决定。
  
      :param str path: 文件的路径
      :return: DataSet
      """
      ds = DataSet()
      for idx, data in _read_conll(
          path, indexes=self.indexes, dropna=self.dropna
      ):
          doc_start = False
          for i, h in enumerate(self.headers):
              field = data[i]
              if str(field[0]).startswith("-DOCSTART-"):
                  doc_start = True
                  break
          if doc_start:
              continue
          ins = {h: data[i] for i, h in enumerate(self.headers)}
          ds.append(Instance(**ins))
      if len(ds) == 0:
          raise RuntimeError("No data found {}.".format(path))
      return ds
  
imports: import glob
  import os
  import random
  import shutil
  import time
  from typing import List
  from .loader import Loader
  from ..file_reader import _read_conll
  from fastNLP.core.dataset import DataSet, Instance
label_desc: Use image node_id 2 for calling the Conll2003NERLoader obj's underlying member method code with example usage: obj._load(path) and returns: ds