code: def _assemble_estimators(self, weights, split_idx):
      coef = utils.to_1d_array(weights)
      return [_linear_to_ast(coef, self._bias[split_idx])]
  
imports: import json
  import math
  import numpy
  from m2cgen import ast
  from m2cgen.assemblers import utils
  from m2cgen.assemblers.base import ModelAssembler
  from m2cgen.assemblers.linear import _linear_to_ast
label_desc: Use image node_id 2 for calling the XGBoostLinearModelAssembler obj's underlying member method code with example usage: obj._assemble_estimators(weights, split_idx) and returns: list