Page through AWS CloudSearch results by pages of a given size with Next and Prev links

cloudsearch_page_size.py

#!/usr/bin/env python3
"""
We want to query of a page 'size' of N results and return them, and also a
'next' and 'previous' link. Those CloudSearch 'start' offsets are based on the
page (for our app, starting at 1) and the size. So with size=100: page=1 has
start=0, page=2 has start=100, page=10 has start=100. We don't want to return
'previous' if we're at page=1, and don't want to return 'next' if it's beyond
the maximum results 'found'.  So if size=100 and found=543, the last page=5,
there is no page=6. More generally: lastpage = int(found / size).
"""

import boto3

cs = boto3.client('cloudsearchdomain',
                  endpoint_url='https://search-mydomain.us-east-1.cloudsearch.amazonaws.com',
                  region_name='us-east-1')


def get_results_page(query, page=1, size=3):
    # If page too low, asking CloudSearch will break it, return only 'next'
    if page < 1:
        return {'previous': None, 'next': 1, 'found': 0, 'results': []}
    # page=1 is our app's first but CloudSearch is 0-based
    start = (page - 1) * size
    ret = cs.search(query=query, start=start, size=size)
    found = ret['hits']['found']
    lastpage = int((found + size - 1) / size)
    # If we ask for too high a page, we do get 'found' from results, return it
    if page > lastpage:
        return {'previous': lastpage, 'next': None, 'found': found, 'results': []}
    hit = ret['hits']['hit']
    prevpage = None
    nextpage = None
    if page > 2:
        prevpage = page - 1
    if page < lastpage:
        nextpage = page + 1
    print('<{}] {} ({}) [{}> {}'.format(
        prevpage or 'X', page, start, nextpage or 'X', ' | '.join([h['id'] for h in hit])))
    return {'previous': prevpage,
            'next': nextpage,
            'found': found,
            'results': ' | '.join([h['id'] for h in hit]),
            }

# Walk the pages starting with 1 and following the 'next' number
page = 1
while True:
    res = get_results_page('nasa', page)
    if not res['next']:
        break
    page += 1

res = get_results_page('nasa', page=1000)
print('Get page too far: {}'.format(res))
print('Get prev page: {}'.format(get_results_page('nasa', page=res['previous'])))

res = get_results_page('nasa', page=0)
print('Get page too low: {}'.format(res))
print('Get next page: {}'.format(get_results_page('nasa', page=res['next'])))

I've got an off-by-one error in here I need to update