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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _get_task_host():
 """Get the Host header value for all mr tasks. Task Host header determines which instance this task would be routed to. Current version id format is: v7.368834058928280579 Current module id is just the module's name. It could be "default" Default version hostname is app_id.appspot.com Returns: A complete host name is of format version.module.app_id.appspot.com If module is the default module, just version.app_id.appspot.com. The reason is if an app doesn't have modules enabled and the url is "version.default.app_id", "version" is ignored and "default" is used as version. If "default" version doesn't exist, the url is routed to the default version. """

  version = os.environ["CURRENT_VERSION_ID"].split(".")[0]
  default_host = os.environ["DEFAULT_VERSION_HOSTNAME"]
  module = os.environ["CURRENT_MODULE_ID"]
  if os.environ["CURRENT_MODULE_ID"] == "default":
    return "%s.%s" % (version, default_host)
  return "%s.%s.%s" % (version, module, default_host)