<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def main(unused_argv):
 """Freeze a model to a GraphDef proto."""

    if FLAGS.use_tpu:
        dual_net.freeze_graph_tpu(FLAGS.model_path)
    else:
        dual_net.freeze_graph(FLAGS.model_path)