code: def _rewrite_params(self, in_obj):
      params = in_obj.params.copy()
      new_shape = list(in_obj.shape)
      new_shape[0] = np.nan
      params["shape"] = tuple(new_shape)
  
      if self.ignore_index:
          params["index_value"] = parse_index(
              pd.RangeIndex(-1), (in_obj.key, in_obj.index_value.key)
          )
      else:
          params["index_value"] = parse_index(
              None, (in_obj.key, in_obj.index_value.key)
          )
      return params
  
file_path: mars/mars/dataframe/base/explode.py
imports: import numpy
  import pandas
  from ...None import opcodes
  from ...core import OutputType, recursive_tile
  from ...serialization.serializables import AnyField, BoolField
  from ...utils import calc_nsplits
  from ..operands import DataFrameOperand, DataFrameOperandMixin
  from ..utils import parse_index, standardize_range_index
label_desc: Use image node_id 4 for calling the DataFrameExplode obj's underlying member method code with example usage: obj._rewrite_params(in_obj) and returns: params