code: def host_hash(salt=None):
      """
      Computes this host's host hash by invoking horovod.runner.common.util.host_hash.host_hash.
  
      Consider environment variable CONTAINER_ID which is present when running Spark via YARN.
      A YARN container does not share memory with other containers on the same host,
      so it must be considered a `host` in the sense of the `host_hash`.
  
      :param salt: extra information to include in the hash, ignores Falsy values
      :return: host hash
      """
      # turn salt into an array of a single string if given
      salt = [str(salt)] if salt else []
  
      # We would violate resource allocation if we run all tasks of a host in one container.
      # See [issues 1497](https://github.com/horovod/horovod/issues/1497) for details.
      container = os.environ.get("CONTAINER_ID")
      if container is not None:
          salt.append(container)
  
      return hh.host_hash(salt="-".join(salt))
  
imports: import horovod.spark.common._namedtuple_fix
  import contextlib
  import os
  import time
  from multiprocessing.pool import ThreadPool
  import pyarrow
  import numpy
  import pyspark.sql.functions
  from pyspark.ml.linalg import DenseVector, SparseVector, Vector, VectorUDT
  from pyspark.sql.types import ArrayType, BinaryType, BooleanType, FloatType, DoubleType, IntegerType, LongType, NullType, StringType
  from pyspark.sql import SparkSession
  from horovod.runner.common.util import codec, host_hash
  from horovod.spark.common import cache, constants
label_desc: Use image node_id 1 for calling a global function with example usage: host_hash(salt) and returns: hh