How to execute the functions from other function depending on value/message of the variables in python?

I have a below function in my python script from where I want to exectute two other functions and these depends on the value of PageId and ver if it is null then it should execute write_data_null(auth, html, title) else it should execute write_data_not_null(auth, html, pageId, title) function.The first function overwrites the data on wiki on the existing page and second function creates the page and write the data on wiki.

To know whether the page exist already I wrote one function which gives me the value of PageId and if it doesn't exist it gives me error message "IndexError: list index out of range" .I am fine with that.My intention is if it gives me this error then I would assume that page doesn't exist and it should execute write_data_null function successfully.

Could someone tell me how could I achieve this?

import argparse
import sys

import requests
import json

BASE_URL = "https://wiki.host.com/rest/api/content"

VIEW_URL = "https://wiki.host.com/pages/viewpage.action?pageId="

def pprint(data):
    '''
    Pretty prints json data.
    '''
    print json.dumps(
        data,
        sort_keys = True,
        indent = 4,
        separators = (', ', ' : '))


def get_page_id(auth, title):

    url = '{base}?title={title}&spaceKey=Nara&expand=history'.format(
        base = BASE_URL,
        title = title)

    r = requests.get(url, auth = auth)

    #print r

    r.raise_for_status()

    return r.json()

def get_page_info(auth, pageId):

    url = '{base}/{pageId}'.format(
        base = BASE_URL,
        pageId = pageId)

    r = requests.get(url, auth = auth)

#    print r

    r.raise_for_status()

    return r.json()


def write_not_data_avail(auth, html, title):

    info = get_page_id(auth, title)

    pageId = int(info['results'][0]['id'])
    #output = pageId.read()
    print pageId

    write_data_not_null(auth, html, pageId, title)


def write_data_null(auth, html, title):

    spec = 'Prolog'

    data = {
        'type' : 'page',
        'title' : str(title),
        'ancestors' : [{'id' : '46306721'}],
        'space' : {'key' : spec},
        'body'  : {
            'storage' :
            {
                'representation' : 'storage',
                'value' : str(html),
            }
        }
    }

    data = json.dumps(data)

    url = '{base}/'.format(base = BASE_URL)

    r = requests.post(
        url,
        data = data,
        auth = auth,
        headers = { 'Content-Type' : 'application/json' }
    )

    r.raise_for_status()

def execute_funtion_in_order(auth, html, title):

    info = get_page_id(auth, title)
    try:
        write_not_data_avail(auth, html, title)
    except:
        write_data_null(auth, html, title)

def write_data_not_null(auth, html, pageId, title):

    info = get_page_info(auth, pageId)

#    print info

    ver = int(info['version']['number']) + 1


    if title is not None:
        info['title'] = title

    data = {
        'id' : str(pageId),
        'type' : 'page',
        'title' : info['title'],
        'version' : {'number' : ver},
        'body'  : {
            'storage' :
            {
                'representation' : 'storage',
                'value' : str(html),
            }
        }
    }

    data = json.dumps(data)

    url = '{base}/{pageId}'.format(base = BASE_URL, pageId = pageId)

    r = requests.put(
        url,
        data = data,
        auth = auth,
        headers = { 'Content-Type' : 'application/json' }
    )

    r.raise_for_status()

    print "Wrote '%s' version %d" % (info['title'], ver)
    print "URL: %s%d" % (VIEW_URL, pageId)


def get_login(user, passwd):
    '''
    Get the password for username and make auth token.
    '''

    if user is None:
        print 'username is empty'

    if passwd is None:
        print 'password is empty'

    return (user, passwd)


def main():

    parser = argparse.ArgumentParser()

    parser.add_argument(
        "-u",
        "--user",
        default = None,
        help = "Specify the username to log into Confluence")

    parser.add_argument(
        "-p",
        "--passwd",
        default = None,
        help = "Specify the username to log into Confluence")

    parser.add_argument(
        "-t",
        "--title",
        default = None,
        type = str,
        help = "Specify a new title")

    parser.add_argument(
        "-f",
        "--file",
        default = None,
        type = str,
        help = "Write the contents of FILE to the confluence page")

    parser.add_argument(
        "html",
        type = str,
        default = None,
        nargs = '?',
        help = "Write the immediate html string to confluence page")

    options = parser.parse_args()

    auth = get_login(options.user, options.passwd)

    if options.html is not None and options.file is not None:
        raise RuntimeError(
            "Can't specify both a file and immediate html to write to page!")

    if options.html:
        html = options.html

    else:

        with open(options.file, 'r') as fd:
            html = fd.read()

    execute_funtion_in_order(auth, html, options.title)


if __name__ == "__main__" : main()