code: def _update_forward_compatibility_date_number(date_to_override=None):
      """Update the base date to compare in forward_compatible function."""
  
      global _FORWARD_COMPATIBILITY_DATE_NUMBER
  
      if date_to_override:
          date = date_to_override
      else:
          date = _FORWARD_COMPATIBILITY_HORIZON
          delta_days = os.getenv(
              _FORWARD_COMPATIBILITY_DELTA_DAYS_VAR_NAME
          )
          if delta_days:
              date += datetime.timedelta(days=int(delta_days))
  
      if date < _FORWARD_COMPATIBILITY_HORIZON:
          logging.warning(
              "Trying to set the forward compatibility date to the past"
              " date %s. This will be ignored by TensorFlow." % (date)
          )
          return
      _FORWARD_COMPATIBILITY_DATE_NUMBER = _date_to_date_number(
          date.year, date.month, date.day
      )
  
file_path: tensorflow-upstream/tensorflow/python/compat/compat.py
imports: import datetime
  import os
  from tensorflow.python.platform import tf_logging
  from tensorflow.python.util import tf_contextlib
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 2 for calling a global function with example usage: _update_forward_compatibility_date_number(date_to_override) without return types