<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def train(input_dir, batch_size, max_steps, output_dir, checkpoint):
 """Train model locally."""

    from google.datalab.utils import LambdaJob

    if checkpoint is None:
      checkpoint = _util._DEFAULT_CHECKPOINT_GSURL

    labels = _util.get_labels(input_dir)
    model = _model.Model(labels, 0.5, checkpoint)
    task_data = {'type': 'master', 'index': 0}
    task = type('TaskSpec', (object,), task_data)
    job = LambdaJob(lambda: _trainer.Trainer(input_dir, batch_size, max_steps, output_dir,
                                             model, None, task).run_training(), 'training')
    return job