Quick Python script to get most contacted gmail users using Gmail api

gistfile1.py

import httplib2
import os

from apiclient import discovery
import oauth2client
from oauth2client import client
from oauth2client import tools
from apiclient.http import BatchHttpRequest
import operator

try:
    import argparse
    flags = argparse.ArgumentParser(parents=[tools.argparser]).parse_args()
except ImportError:
    flags = None

SCOPES = 'https://www.googleapis.com/auth/gmail.readonly'
CLIENT_SECRET_FILE = 'client_secret.json'
APPLICATION_NAME = 'Gmail API Quickstart'

from collections import defaultdict
d = defaultdict(int)

def get_credentials():
    """Gets valid user credentials from storage.

    If nothing has been stored, or if the stored credentials are invalid,
    the OAuth2 flow is completed to obtain the new credentials.

    Returns:
        Credentials, the obtained credential.
    """
    home_dir = os.path.expanduser('~')
    credential_dir = os.path.join(home_dir, '.credentials')
    if not os.path.exists(credential_dir):
        os.makedirs(credential_dir)
    credential_path = os.path.join(credential_dir,
                                   'gmail-quickstart.json')

    store = oauth2client.file.Storage(credential_path)
    credentials = store.get()
    if not credentials or credentials.invalid:
        flow = client.flow_from_clientsecrets(CLIENT_SECRET_FILE, SCOPES)
        flow.user_agent = APPLICATION_NAME
        if flags:
            credentials = tools.run_flow(flow, store, flags)
        else: # Needed only for compatability with Python 2.6
            credentials = tools.run(flow, store)
        print 'Storing credentials to ' + credential_path
    return credentials

def main():
    """Shows basic usage of the Gmail API.

    Creates a Gmail API service object and outputs a list of label names
    of the user's Gmail account.
    """
    pages = 0
    limit = 1 #Only consider 1000 sent emails for now. This seems to give a good enough sample.  300 is probably also sufficient.
    credentials = get_credentials()
    http = credentials.authorize(httplib2.Http())
    service = discovery.build('gmail', 'v1', http=http)

    response = service.users().messages().list(userId='me',labelIds=['SENT'], maxResults="1000").execute()
    messages = []
    if 'messages' in response:
        messages.extend(response['messages'])
    while ('nextPageToken' in response) and (pages < limit):
        page_token = response['nextPageToken']
        response = service.users().messages().list(userId='me', pageToken=page_token,labelIds=['SENT'],).execute()
        messages.extend(response['messages'])
        pages = pages + 1

    batch = BatchHttpRequest(callback=getmail)

    for msg_id in messages:
        batch.add(service.users().messages().get(userId='me', id=msg_id['id'],format="metadata",
            metadataHeaders="to"))
    batch.execute(http = http)

    sorted_d = sorted(d.items(), key=operator.itemgetter(1),reverse=True)[0:20]
    print(sorted_d)

def getmail(request_id, response, exception):
    if exception is not None:
        pass
    else:
        print response
        try:
            friend_email = response["payload"]["headers"][0]["value"]
            d[friend_email] +=1
        except:
            print("Error")
        pass


if __name__ == '__main__':
    main()