code: def optional_tuning_records(log_filename):
      """Returns existing tuning records, if any."""
      if log_filename == "" or not os.path.exists(log_filename):
          return tvm.autotvm.task.FallbackContext()
      else:
          return tvm.autotvm.task.ApplyHistoryBest(log_filename)
  
imports: import tvm
  import logging
  import tempfile
  import os
  import shutil
  import menangerie
  from tvm.relay.op.contrib.cutlass import partition_for_cutlass
  from tvm.contrib.cutlass import num_cutlass_partitions
  from tvm.relay.op.contrib.cublas import partition_for_cublas
  from tvm.relay.op.contrib.cudnn import partition_for_cudnn
label_desc: Use image node_id 2 for calling a global function with example usage: optional_tuning_records(log_filename) and returns: tvm, tvm