code: def _assemble_tree(self, tree):
      raise NotImplementedError
  
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 3 for calling the BaseTreeBoostingAssembler obj's underlying member method code with example usage: obj._assemble_tree(tree) without return types