docstr: Returns number of categories
docstr_tok: ["Returns","number","of","categories"]
code: def num_categories(self):
      """
      Returns number of categories
      """
      return len(self.model.names)
  
file_path: sahi/sahi/models/yolov8.py
imports: import logging
  from typing import Any, Dict, List, Optional
  import numpy
  from sahi.models.base import DetectionModel
  from sahi.prediction import ObjectPrediction
  from sahi.utils.compatibility import fix_full_shape_list, fix_shift_amount_list
  from sahi.utils.import_utils import check_requirements
label_desc: Use image node_id 6 for calling the Yolov8DetectionModel obj's underlying member method code with example usage: obj.num_categories() and returns: len