code: def july_5th_holiday_observance(datetime_index):
      return datetime_index[datetime_index.year != 2013]
  
imports: from contextlib import contextmanager
  from copy import deepcopy
  from itertools import product
  import operator
  import warnings
  import numpy
  import pandas
  from distutils.version import StrictVersion
  from trading_calendars.utils.pandas_utils import days_at_time
label_desc: Use image node_id 1 for calling a global function with example usage: july_5th_holiday_observance(datetime_index) and returns: datetime_index