code: def try_gpu(index, query, reference, k, is_cuda, gpus):
      # https://github.com/facebookresearch/faiss/blob/master/faiss/gpu/utils/DeviceDefs.cuh
      gpu_index = None
      gpus_are_available = faiss.get_num_gpus() > 0
      gpu_condition = (
          is_cuda or (gpus is not None)
      ) and gpus_are_available
      if gpu_condition:
          max_k_for_gpu = (
              1024 if float(torch.version.cuda) < 9.5 else 2048
          )
          if k <= max_k_for_gpu:
              gpu_index = convert_to_gpu_index(index, gpus)
      try:
          return add_to_index_and_search(gpu_index, query, reference, k)
      except (AttributeError, RuntimeError):
          if gpu_condition:
              c_f.LOGGER.warning(
                  f"Using CPU for k-nn search because k = {k} > {max_k_for_gpu}, which is the maximum allowable on GPU."
              )
          cpu_index = convert_to_cpu_index(index)
          return add_to_index_and_search(cpu_index, query, reference, k)
  
imports: import numpy
  import torch
  from ..distances import BatchedDistance, CosineSimilarity
  from .None import common_functions
label_desc: Use image node_id 4 for calling a global function with example usage: try_gpu(index, query, reference, k, is_cuda, gpus) and returns: add_to_index_and_search, add_to_index_and_search