code: def create_agent(opt: Opt, requireModelExists=False):
      """
      Create an agent from the options ``model``, ``model_params`` and ``model_file``.
  
      The input is either of the form
      ``parlai.agents.ir_baseline.agents:IrBaselineAgent`` (i.e. the path
      followed by the class name) or else just ``ir_baseline`` which
      assumes the path above, and a class name suffixed with 'Agent'.
  
      If ``model-file`` is available in the options this function can also
      attempt to load the model from that location instead. This avoids having to
      specify all the other options necessary to set up the model including its
      name as they are all loaded from the options file if it exists (the file
      opt['model_file'] + '.opt' must exist and contain a pickled or json dict
      containing the model's options).
      """
      if opt.get("datapath", None) is None:
          add_datapath_and_model_args(opt)
  
      if opt.get("model_file"):
          opt["model_file"] = modelzoo_path(
              opt.get("datapath"), opt["model_file"]
          )
          if requireModelExists and not PathManager.exists(
              opt["model_file"]
          ):
              raise RuntimeError(
                  "WARNING: Model file does not exist, check to make "
                  "sure it is correct: {}".format(opt["model_file"])
              )
          # Attempt to load the model from the model file first (this way we do
          # not even have to specify the model name as a parameter)
          model = create_agent_from_opt_file(opt)
          if model is not None:
              return model
          else:
              logging.info(
                  f"No model with opt yet at: {opt['model_file']}(.opt)"
              )
  
      if opt.get("model"):
          model_class = load_agent_module(opt["model"])
          # if we want to load weights from --init-model, compare opts with
          # loaded ones
          compare_init_model_opts(opt, opt)
          model = model_class(opt)
          if (
              requireModelExists
              and hasattr(model, "load")
              and not opt.get("model_file")
          ):
              # double check that we didn't forget to set model_file on loadable model
              logging.warning(
                  "model_file unset but model has a `load` function."
              )
          return model
      else:
          raise RuntimeError(
              "Need to set `model` argument to use create_agent."
          )
  
imports: import copy
  from typing import List, Union
  from parlai.core.build_data import modelzoo_path
  from parlai.core.loader import load_agent_module
  from parlai.core.loader import register_agent
  from parlai.core.message import Message
  from parlai.core.opt import Opt
  from parlai.utils.misc import warn_once
  import parlai.utils.logging
  from parlai.utils.io import PathManager
label_desc: Use image node_id 5 for calling a global function with example usage: create_agent(opt, requireModelExists) and returns: model, model