python FTP 上传文件

#coding=utf-8
from ftplib import FTP

HOST = '12.11.13.12'
PORT = '21'
USER = 'test'
PWD = 'test'

def main(filename):
    try:
        ftp=FTP()
        ftp.connect(HOST,PORT)
    except:
        return 2
    try:
        ftp.login(USER,PWD)
    except:
        ftp.quit()
        return 3
    try:
        info = ftp.getwelcome()
        )
        file_obj = open(filename,'rb')
        ftp.storlines('STOR %s' %filename, file_obj)
        return 0
    except:
        return 1
    finally:
        try: file_obj.close()
        except: pass
        try: ftp.quit()
        except: pass