understanding multiple python 'with open' file functions -

i'm having difficult time understanding second 'with open' function here.

so, in first 'with open' part, we've said out = open(save_as_file, 'wb+') , right? (still new using 'with open'). later write , 'with open' automatically closes 'out' file.that part - we're writing response object requests binary in specified save_as_file location until hit 81920th character aka our buffer #.

what's going on in second 'with open'? breaking down same way above, it's pretty fp = open(save_as_file, 'r') , right? make fp, assigned request response object earlier? we're opening save_as_file use reading not reading or extracting it, don't see reason it. if explain in english what's taking place , purpose of second 'with open' part, appreciated.

(don't worry load_from_file function @ end, that's function under class)

def load_from_url(self, url, save_as_file=none):      fp = requests.get(url, stream=true,                       headers={'accept-encoding': none}).raw      if save_as_file none:         return self.load_from_file(fp)      else:         open(save_as_file, 'wb+') out:             while true:                 buffer = fp.read(81920)                 if not buffer:                     break                 out.write(buffer)         open(save_as_file) fp:             return self.load_from_file(fp) 

you correct second with statement opens file reading.

what happens this:

1. load response url
2. if save_as_file none:
   1. call load_from_file on response , return result
3. else:
   1. store contents of response save_as_file
   2. call load_from_file on contents of file , return result

so essentialy, if save_as_file set stores response body in file, processes , returns processed result. otherwise processes response body , returns result.

the way implemented here because load_from_file expects file-like object , easiest way programmer saw of obtaining read file back.

it done keeping response body in memory , using python 3's io module or python 2's stringio provide file-like object uses response body memory, thereby avoiding need read file again.

fp reassigned in second with statement in same way other variable if assigned value.