Resuming with (ftplib/httplib)?

[Orlando Vazquez]

Hi, I want to write a program in Python similar to GetRight or Greed,
which are download managers. The killer feature of these programs is
that you can resume a download if you get disconnected. This means you
can finish at a later time without having to redownload whatever you've
already got.
So my question is, how can I, using ftplib and httplib, resume a
download? Is it possible? Has this been done before? Any code someone
would be willing to share? I would appreciate it soo much. :-)

Orlando Vazquez