code: def _multi_class_convert_output(self, exprs):
      supported_objectives = {
          "multiclass": super()._multi_class_convert_output,
          "multiclassova": self._multi_class_sigmoid_transform,
          "custom": super()._single_convert_output,
      }
      if self.objective_name not in supported_objectives:
          raise ValueError(
              f"Unsupported objective function '{self.objective_name}'"
          )
      return supported_objectives[self.objective_name](exprs)
  
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 LightGBMModelAssembler obj's underlying member method code with example usage: obj._multi_class_convert_output(exprs) and returns: supported_objectives