code: def _fetch_data(data_key: str, band: str = None):
      # do nothing actually
      ctx = get_context()
      assert ctx.band == band
      with Timer() as timer:
          ctx.get_chunks_result([data_key], fetch_only=True)
      return timer.duration
  
file_path: mars/benchmarks/asv_bench/benchmarks/storage.py
imports: import itertools
  import cloudpickle
  import numpy
  import pandas
  import mars
  import mars.remote
  from mars.core.context import get_context
  from mars.utils import Timer, readable_size
label_desc: Use image node_id 3 for calling a global function with example usage: _fetch_data(data_key, band) and returns: timer