Export Youtube Channel Videos to CSV using Python3 + Youtube Api

export_yt_channel_videos_to_csv.py

import requests  # or urllib
import csv


# get Youtube Data API Key
API_KEY = ""  # insert your API key
# youtube channel ID
channel_id = ""  # insert Youtube channel ID
page_token = ""

videos = []

next = True
while next:
    url = ("https://www.googleapis.com/youtube/v3/search?key="
            "{}&channelId={}&part=snippet,id"
            "&order=date&maxResults=50&pageToken={}"
            ).format(
                API_KEY,
                channel_id,
                page_token
            )
    resp = requests.get(url)
    data = resp.json()

    for i in data['items']:
        videos.append(i)

    # iterate through result pagination
    is_next = data.get('nextPageToken')
    if is_next:
        page_token = is_next
    else:
        next = False

# structuring the data
rows = []
for i in videos:
    title = i['snippet'].get('title')
    description = i['snippet'].get('description', "")
    videoId = "https://www.youtube.com/watch?v={}".format(
        i['id'].get('videoId', ""))
    # add special formula [=image("url")], so we can view the thumbnail in google docs spreadsheet
    thumb = "=image(\"{}\")".format(i['snippet']['thumbnails'].get('default').get('url', ""))
    rows.append(";".join([title, description, videoId, thumb]))
    # data is now ready to write to csv file

# writing to csv file
path = "videos.csv"
with open(path, "w") as csv_file:
    writer = csv.writer(csv_file, delimiter=";")
    for row in rows:
        writer.writerow(row.split(";"))

Hi, im pretty interested in use this program in order to use its output into an R script which aims to do some basic data analysis about a given youtube channel.
Unfortunately, I'm much of a noobie about this issues so there are some details i'm struggling to get yet.

What's the meaning of page_token, and how am I supposed to get it?

So sorry, as this will be probably an obvious question for you, and thank you in advance.