code: def get_calendar_minute(freq="day", future=False):
      """Load High-Freq Calendar Minute Using Memcache"""
      flag = f"{freq}_future_{future}_day"
      if flag in H["c"]:
          _calendar = H["c"][flag]
      else:
          _calendar = np.array(
              list(
                  map(
                      lambda x: x.minute // 30,
                      Cal.load_calendar(freq, future),
                  )
              )
          )
          H["c"][flag] = _calendar
      return _calendar
  
imports: import numpy
  import pandas
  from datetime import datetime
  from qlib.data.cache import H
  from qlib.data.data import Cal
  from qlib.data.ops import ElemOperator, PairOperator
  from qlib.utils.time import time_to_day_index
label_desc: Use image node_id 2 for calling a global function with example usage: get_calendar_minute(freq, future) and returns: _calendar