docs: def downloadFile(url,outfile=None): 
      ''' Copied from  http://stackoverflow.com/questions/16694907/how-to-download-large-file-in-python-with-requests-py '''
      if not outfile:
          outfile = url.split('/')[-1]
      r = requests.get(url, stream=True)
      with open(outfile, 'wb') as f:
          for chunk in r.iter_content(chunk_size=1024): 
              if chunk: 
                  f.write(chunk)
      return outfile