input: Write a function named "Transpile" that takes in four arguments: "src_dir", "dst_dir", "model_filename", and "params_filename". The function should create a CPUPlace object and an Executor object using Paddle Fluid. Next, it should create a Scope object and load the inference program, feed target names, and fetch targets using fluid.io.load_inference_model(). The function should then clone the inference program and apply the inference transpiler using fluid.InferenceTranspiler(). The optimized inference program should be saved to "dst_dir" using fluid.io.save_persistables(). If "dst_dir" does not exist, it should be created using os.makedirs(). Finally, create a main function that takes in arguments using argparse.ArgumentParser() and calls the "Transpile" function with the parsed arguments.
  
  assert Transpile("test_src", "test_dst", "model.pdmodel", "model.pdiparams") == None
  assert Transpile("test_src", "test_dst_missing", "model.pdmodel", "model.pdiparams") == None
  assert Transpile("test_src_nonexistent", "test_dst", "model.pdmodel", "model.pdiparams") == None
  assert Transpile("test_src", "test_dst", "model_nonexistent.pdmodel", "model.pdiparams") == None
  assert Transpile("", "test_dst", "model.pdmodel", "model.pdiparams") == None
output: 
  def Transpile(src_dir, dst_dir, model_filename, params_filename):
      import paddle.fluid as fluid
      import os
      
      place = fluid.CPUPlace()
      exe = fluid.Executor(place)
      scope = fluid.core.Scope()
      
      with fluid.scope_guard(scope):
          [inference_program, feed_target_names, fetch_targets] = fluid.io.load_inference_model(
              dirname=src_dir,
              executor=exe,
              model_filename=model_filename,
              params_filename=params_filename
          )
          
          transpiler = fluid.InferenceTranspiler()
          transpiler.transpile(inference_program, place)
          
          if not os.path.exists(dst_dir):
              os.makedirs(dst_dir)
          
          fluid.io.save_persistables(
              executor=exe,
              dirname=dst_dir,
              main_program=inference_program
          )
  