code: def accelerator_from_sku(sku) -> Optional[str]:
      description = sku["description"]
      if description.startswith("Nvidia L4 GPU"):
          return "l4"
      return None
  
imports: import logging
  from typing import AsyncGenerator, List, Optional
  from hailtop.aiocloud import aiogoogle
  from hailtop.utils import rate_cpu_hour_to_mcpu_msec, rate_gib_hour_to_mib_msec, rate_gib_month_to_mib_msec, rate_instance_hour_to_fraction_msec
  from hailtop.utils.time import parse_timestamp_msecs
  from ....driver.pricing import Price
  from ..resources import GCPAcceleratorResource, GCPComputeResource, GCPLocalSSDStaticSizedDiskResource, GCPMemoryResource, GCPStaticSizedDiskResource
label_desc: Use image node_id 4 for calling a global function with example usage: accelerator_from_sku(sku) and returns: None, str