code: def count_available_slots(self):
      # Use the host_assignment_order as it does not contain blacklisted hosts
      return sum(
          [self.get_slots(host) for host in self._host_assignment_order]
      )
  
imports: import io
  import logging
  import random
  import threading
  import time
  from collections import defaultdict
  from horovod.runner.common.util import safe_shell_exec
  from horovod.runner.elastic.worker import HostUpdateResult
label_desc: Use image node_id 6 for calling the DiscoveredHosts obj's underlying member method code with example usage: obj.count_available_slots() and returns: sum