<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def cleanup_files_on_ev3():
 """cleanup files in homedir on EV3."""


    list = get_base_ev3dev_cmd() + ['cleanup']

    env = os.environ.copy()
    env["PYTHONUSERBASE"] = THONNY_USER_BASE
    proc = subprocess.Popen(list, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                            universal_newlines=True, env=env)
    dlg = MySubprocessDialog(get_workbench(), proc, "Delete files in homedir on EV3", autoclose=False)
    dlg.wait_window()