Complete download file over FTP example. Complete with write-report closure in python3 style, writing stdout to same line and nice verbosity handling

ftp-download.py

#!/usr/bin/env python3

from ftplib import FTP

def ftp_download(server,remote_path,local_path,username="anonymous",password="",verbose=True):
        #new ft object
        ftp = FTP(server) 
        if verbose: print("Connected to %s"%server)
        
        #notice that default login is "anonymous" with no password. works on most public servers
        ftp.login(username,password)
        if verbose: print("Logged in as %s"%username)

        #get size of the desired file
        size = ftp.size(remote_path)
        if verbose: print("Download size %sb"%size)

        #measure download progress
        downloaded = 0.0
        chunksize = 8192
        with open(local_path,"wb") as output_file:
                
                #python3 style closure using nonlocal keyword to grab parental values
                def _dl_write(chunk):
                        nonlocal size
                        nonlocal downloaded
                        nonlocal chunksize
                        output_file.write(chunk) 
                        downloaded+=chunksize
                        
                        #end="\r" allows us to overwrite the output on the same line
                        print("%.1f%%"%(downloaded/size*100),end="\r")
                        
                if verbose: print("Downloading %s"%remote_path)
                ftp.retrbinary("RETR %s"%remote_path,callback = _dl_write)
        print("Done")
        ftp.quit()

def main:
        ftp_download("ftp.example.com","path/to/remote/file","path/to/local/file")