Python3 - upload all files in folder (FTP)

import time
import sys

#put this file in your /bin/THISFILE
#upload files only python3
print("mycloud v0.1")

time.sleep(1)

if len(sys.argv) == 4:
        FILENAME = []

        HOST = str(sys.argv[1])
        USER = str(sys.argv[2])
        PASS = str(sys.argv[3])

        ftp = FTP(HOST)

        if ftp:
                print(ftp)
        else:
                print("ERROR: Could not connect to {}".format(HOST))
                sys.exit(1)
        login = ftp.login(user=USER, passwd=PASS)

        if login:
                print(login)
        else:
                print("ERROR: Could not Login to FTP Server!")
                sys.exit(1)
else:
        print("ERROR: FILE <ip> <username> <password>")
        sys.exit(1)
def upload_file(FILENAME):
        for f in os.listdir(os.curdir):
                if os.path.isfile(f):
                        FILENAME.append(f)

        for get_names in FILENAME:
                UPLOAD_FILE = ftp.storbinary('STOR ' + get_names, open(get_names, 'rb'))

                if UPLOAD_FILE:
                        print("sucsessfully uploaded {} - {}".format(get_names,UPLOAD_FILE))
                else:
                        print("ERROR: Could not upload {} - {}".format(get_names,UPLOAD_FILE))


        ftp.quit()

upload_file(FILENAME)