code: def is_valid_slot(slot):
      return slot.startswith("B-") or slot.startswith("I-")
  
file_path: pytext/demo/atis_joint_model/data_processor.py
imports: import os
  import random
  import click
  from pytext.utils.file_io import PathManager
label_desc: Use image node_id 4 for calling a global function with example usage: is_valid_slot(slot) and returns: unknown