class_docstr: 将类似于 ``[[1], [1, 2]]`` 的内容 pad 为 ``[[1, 0], [1, 2]]`` 。可以 pad 多重嵌套的数据。
  
  :param pad_val: pad 的值；
  :param ele_dtype: 用于检测当前 field 的元素类型是否可以转换为 :class:`np.array` 类型；
  :param dtype: 输出的数据的 dtype ；
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docstr: :param batch_field: 输入的某个 field 的 batch 数据。
  :param pad_val: 需要填充的值
  :param dtype: 该参数无意义。
  :return:
docstr_tok: [":","param","batch_field",":","\u8f93\u5165\u7684\u67d0\u4e2a","field","\u7684","batch","\u6570\u636e\u3002",":","param","pad_val",":","\u9700\u8981\u586b\u5145\u7684\u503c",":","param","dtype",":","\u8be5\u53c2\u6570\u65e0\u610f\u4e49\u3002",":","return",":"]
code: def pad(batch_field, pad_val=0, dtype=None):
      """
  
      :param batch_field: 输入的某个 field 的 batch 数据。
      :param pad_val: 需要填充的值
      :param dtype: 该参数无意义。
      :return:
      """
      return get_padded_numpy_array(
          batch_field, dtype=dtype, pad_val=pad_val
      ).tolist()
  
file_path: fastNLP/fastNLP/core/collators/padders/raw_padder.py
imports: from .padder import Padder
  from .utils import is_number, get_padded_numpy_array, is_number_or_numpy_number
  from .exceptions import *
label_desc: Use image node_id 2 for calling the RawSequencePadder obj's underlying member method code with example usage: obj.pad(batch_field, pad_val, dtype) and returns: get_padded_numpy_array