Make a file in s3 public using python and boto

I have thins link below, and when I try to acess it it appears an xml file saying "Acess denied".

And I need to go to aws managment console and make this part-0000 file public so I can acess it.

Do you know how can I give permissions using boto with python so I can acess this link without needed to go to aws managmet console and make the file public?

downloadLink = 'http://ift.tt/1NF0vFN'