Python redirect checker

python_url_checker.py

#!/usr/bin/python

import csv
import requests

csv_data_to_write = [['original url', 'destination url',
                      'final http status', 'redirect path']]

def redirect_history(history):
    '''repack urls to a neat list'''
    
    hops = []
    for response in history:
        hops.append(response.url)
    
    history = ' -> '.join(hops)
    
    return history

def parse_file(filename='redirects_to_check.txt'):
    '''parse a csv file of redirects and generate a results csv'''
    
    with open(filename, 'rb') as redirect_file:
        reader = csv.reader(redirect_file, delimiter=',')
        for line in reader:
            source_url = line[0]
            destination_url = line[1]
            reponse_text=''
            response_status_code=''
            response_history=''
            
            csv_row_to_write = []
            
            csv_row_to_write.append(source_url)
            csv_row_to_write.append(destination_url)
            
            try:
                response = requests.head(source_url, allow_redirects=True,
                                         timeout=20)
            except Exception as e:
                response = None
                response_text = e
            
            if response != None:
                response_status_code=response.status_code
                response_history = redirect_history(response.history)
                for hop in response.history:
                    if hop.url == destination_url:
                        response_text = 'successful'
                        
            csv_row_to_write.append(response_text)
            csv_row_to_write.append(response_status_code)
            csv_row_to_write.append(response_history)
                
            csv_data_to_write.append(csv_row_to_write)

def write_results():
    '''helper function for writing out csv'''
    with open('redirects_results.csv', 'w') as fp:
        a = csv.writer(fp, delimiter=',')
        a.writerows(csv_data_to_write)

#kick the process off
parse_file()

#write the results
write_results()