Calling the Google Books API to categorize books using ISBN

books.py

import pandas as pd, requests, json, csv

df = pd.ExcelFile('books.xlsx').parse('Sheet1')
df1=df['ISBN13']
isbn_list = df1.tolist()
headers = {
    'apikey': 'API-KEY-HERE'
}

for i in isbn_list:
	response = requests.get(
		'https://www.googleapis.com/books/v1/volumes?q=isbn:' + str(int(i)),
		headers=headers)
	jsonRes = json.loads(response.text)
	if jsonRes['totalItems']!=0:
		if not(jsonRes['items'][0]['volumeInfo'].get('categories')) is None:
			print str(jsonRes['items'][0]['volumeInfo']['categories'])
			with open('categories.csv',"a") as csvfile:
				bookwriter = csv.writer(csvfile, delimiter=' ',
                            quotechar='|', quoting=csv.QUOTE_MINIMAL)
				bookwriter.writerow(jsonRes['items'][0]['volumeInfo']['categories'])
		else:
			print 'category does not exist'
			with open('categories.csv',"a") as csvfile:
				bookwriter = csv.writer(csvfile, delimiter=' ',
                            quotechar='|', quoting=csv.QUOTE_MINIMAL)
				bookwriter.writerow('category does not exist')
	else:
		print 'does not exist'
		with open('categories.csv',"a") as csvfile:
			bookwriter = csv.writer(csvfile, delimiter=' ',
                            quotechar='|', quoting=csv.QUOTE_MINIMAL)
			bookwriter.writerow('does not exist')