ftp_downloder.py

import ftplib # https://pastebin.com/0mhRBnBe

def ftp_download(dir_path, ftp_file):
    try:
        ftp = ftplib.FTP('website.net')
        ftp.login(user = 'user', passwd = 'password')
        ftp.cwd('/public_html/{0}'.format(dir_path))

        ftp.retrbinary('RETR {0}'.format(ftp_file), open(ftp_file, 'wb').write, 1024)
        ftp.storbinary('STOR {0}'.format(ftp_file), open(ftp_file, 'rb'))
        ftp.quit()

        print ('Succes download file: {0}'.format(ftp_file))

    except Exception as ftp_error:
        print (ftp_error)

print ('Welcome to ftplib!')
dir_path = input('Type path location.\n Example: {0}: '.format('wp-content/js_composer/ or None for dir <public_html>'))
ftp_file = input('Type ftp_file.\n Example: {0}: '.format('js_composer.php'))

ftp_download(['', dir_path][dir_path is not 'None'], ftp_file)