Script to post new subreddit posts to a Discord channel via webhook

reddit-feed.py

# Loops through a 2d array like: (1. Subredit name 2. Discord webhook link 3. Type: Hot | New | Top | Rising) and performs the actions to post the posts to the webhooked discord server. also changed the 1second wait to 2 seconds as i was still seeing the web request error.

import requests
import json
import time
from discord_webhook import DiscordWebhook, DiscordEmbed

i = 0

def right(value, count):
    # To get right part of string, use negative first index in slice.
    return value[-count:]

#array columns 1. Subredit name 2. Discord webhook link 3. Type: Hot | New | Top | Rising
myarray = [
    ["discordapp","<discord webhook link here>","hot"]
    ]

#posts new posts for each subreddit to discord
for item in range(0,len(myarray)):
   
    #set up variables
    webhook_url = str(myarray[i][1])
    subreddit = str(myarray[i][0]) # can be chained with + (example: python+webdev)
    rtype = str(myarray[i][2])
    dbname = str(subreddit + right(webhook_url,4) + ".json")

    # open the cache, or start from a blank list
    try:
        with open(dbname) as json_file:
            db = json.load(json_file)
    except FileNotFoundError:
        db = []

    req = requests.get(f'https://www.reddit.com/r/{subreddit}/{rtype}/.json', headers={
        "Cache-Control": "no-cache",
        "Pragma": "no-cache",
        "User-Agent": "discord-feed-bot"})

    posts = req.json()['data']['children']

    # for each new post found in this request
    for post in posts:
        if post['data']['name'] not in db:
            webhook = DiscordWebhook(url=webhook_url)
            permalink = f"https://www.reddit.com{post['data']['permalink']}"

            # create an appropriate embed object
            if post['data']['thumbnail'] == 'self': # text post
                embed = DiscordEmbed(title=post['data']['title'], url=permalink, description=post['data']['selftext'])
                embed.set_footer(text=f"Posted by {post['data']['author']}")
            elif post['data']['is_video']: # video post
                embed = DiscordEmbed(title=post['data']['title'], url=permalink)
                embed.set_image(url=post['data']['thumbnail'])
                embed.set_footer(text=f"Video posted by {post['data']['author']}")
            else: # image post
                embed = DiscordEmbed(title=post['data']['title'], url=permalink)
                embed.set_image(url=post['data']['url'])
                embed.set_footer(text=f"Image posted by {post['data']['author']}")

            # attach the embed to the webhook request and go!
            webhook.add_embed(embed)
            webhook.execute()
            time.sleep(2) # to prevent Discord webhook rate limiting

            # add post name to DB so we don't display it again
            db.append(post['data']['name'])

    # save the cache of (at least) the last 50 posts seen
    with open(dbname, 'w') as outfile:
        json.dump(db[-50:], outfile)
        
    i= i + 1

can you please tell me how i can implement this? which needs to be added in this code? no i need to create a cache file/ folder?