code: def prepend_user_agent(client):
      """Placeholder docstring"""
      prefix = determine_prefix(client._client_config.user_agent)
  
      if client._client_config.user_agent is None:
          client._client_config.user_agent = prefix
      else:
          client._client_config.user_agent = "{} {}".format(
              prefix, client._client_config.user_agent
          )
  
imports: from __future__ import absolute_import
  import platform
  import sys
  import importlib_metadata
label_desc: Use image node_id 2 for calling a global function with example usage: prepend_user_agent(client) without return types