code: def preemptible_from_sku(sku: dict) -> Optional[bool]:
      category = sku["category"]
      usageType = category["usageType"]
  
      if usageType == "OnDemand":
          return False
      if usageType == "Preemptible":
          return True
      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 5 for calling a global function with example usage: preemptible_from_sku(sku) and returns: None, False, True