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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 _prepare_for_training(self, job_name=None):
 """Set hyperparameters needed for training. This method will also validate ``source_dir``. Args: * job_name (str):
 Name of the training job to be created. If not specified, one is generated, using the base name given to the constructor if applicable. """

        super(Framework, self)._prepare_for_training(job_name=job_name)

        # validate source dir will raise a ValueError if there is something wrong with the
        # source directory. We are intentionally not handling it because this is a critical error.
        if self.source_dir and not self.source_dir.lower().startswith('s3://'):
            validate_source_dir(self.entry_point, self.source_dir)

        # if we are in local mode with local_code=True. We want the container to just
        # mount the source dir instead of uploading to S3.
        local_code = get_config_value('local.local_code', self.sagemaker_session.config)
        if self.sagemaker_session.local_mode and local_code:
            # if there is no source dir, use the directory containing the entry point.
            if self.source_dir is None:
                self.source_dir = os.path.dirname(self.entry_point)
            self.entry_point = os.path.basename(self.entry_point)

            code_dir = 'file://' + self.source_dir
            script = self.entry_point
        else:
            self.uploaded_code = self._stage_user_code_in_s3()
            code_dir = self.uploaded_code.s3_prefix
            script = self.uploaded_code.script_name

        # Modify hyperparameters in-place to point to the right code directory and script URIs
        self._hyperparameters[DIR_PARAM_NAME] = code_dir
        self._hyperparameters[SCRIPT_PARAM_NAME] = script
        self._hyperparameters[CLOUDWATCH_METRICS_PARAM_NAME] = self.enable_cloudwatch_metrics
        self._hyperparameters[CONTAINER_LOG_LEVEL_PARAM_NAME] = self.container_log_level
        self._hyperparameters[JOB_NAME_PARAM_NAME] = self._current_job_name
        self._hyperparameters[SAGEMAKER_REGION_PARAM_NAME] = self.sagemaker_session.boto_region_name