code: def _prepare_threshold():
      try:
          return float(os.environ["PREPARE_THRESHOLD"])
      except (KeyError, ValueError):
          return DEFAULT_PREPARE_THRESHOLD
  
imports: import csv
  import logging
  import os
  import re
  import sys
  import time
  from guild import batch_util
  from guild import cli
  from guild import op_util
  from guild import run_util
  from guild import tfevent
  from guild import util
  from .None import runs_impl
label_desc: Use image node_id 7 for calling a global function with example usage: _prepare_threshold() and returns: float, DEFAULT_PREPARE_THRESHOLD