Unless otherwise specified, the following applies to all snippets:

from telethon import TelegramClient, sync, errors
from telethon.tl import functions as f, types as t
client = TelegramClient(...).start()  # successfully logged in

Delete all migrated chats from your dialogs

for d in client.iter_dialogs():
if d.is_group and not d.is_channel:
if d.entity.migrated_to:
client(f.messages.DeleteHistoryRequest(d.input_entity.chat_id, client.get_messages(d.input_entity)[0].id, False))

#delete #migrated

Counts the amount of photos above/below a given size threshold

threshold = 75 * 1024 # 75kb
below = 0
above = 0
chat = 'mychat'
filter = t.InputMessagesFilterPhotos

for m in client.iter_messages(chat, filter=filter):
  if m.photo.sizes[-1].size < threshold:
    below += 1
  else:
    above += 1
print('Below: {}\nAbove: {}\nTotal: {}'.format(below, above, below + above))

#count #media #photos

Reply to a message with "haste" to upload to hastebin and edit your message to the URL
Note: does not handle failure of http request.

import requests

@client.on(events.NewMessage(outgoing=True, pattern="(?i)^haste$"))
def haste(e):
  if e.is_reply and e.get_reply_message().message:
    text = e.get_reply_message().text
    e.edit("[Haste link to the above](https://hastebin.com/{}) ".format(requests.post("https://hastebin.com/documents", data=text).json()['key']))

#hastebin #haste

Block, report and clear all new PMs. Use with caution

whitelist = {d.id for d in client.get_dialogs() if d.id > 0}

@client.on(events.NewMessage)
async def handler(event):
    if not event.is_private or event.chat_id in whitelist:
      return
    who = await event.get_input_chat()
    await client(f.messages.ReportSpamRequest(who))
    await client(f.contacts.BlockRequest(who))
    await client(f.messages.DeleteHistoryRequest(who, 0))

#block #PM #report

Get % of people who participated in the last 5000 messages

group = 'somegroup'
people = {}
total = client.get_participants(group, limit=0).total
for m in client.iter_messages(group, limit=5000):
  if not m.sender.bot:
    people[m.sender.id] = m.sender.first_name
print(len(people)/total)

#analytics #stats #participation

Get the usage count of the top 50 words in the chat

class custom(dict):
def __missing__(self, key): return 0

words = custom()
progress = event.reply("Processed 0 messages")
total = 0
for msg in client.iter_messages(group):
total += 1
if total % 200 == 0:
progress.edit("Processed {} messages".format(total))
if msg.text:
for word in msg.text.split():
words[word.lower()] += 1
global freq
freq = sorted(words, key=words.get, reverse=True)
out = ""
for i in range(51):
out += "{}. {}:{}\n".format(i+1, words[freq[i]], freq[i])

progress.edit(out, parse_mode=None)

#analytics #stats #words

Helper function for determining how long ago a user was online.
Sample usage: within_6_days = [x for x in client.iter_participants(group) if online_within(x, 6)]

import datetime

def online_within(participant, days):
    status = participant.status
    if isinstance(status, t.UserStatusOnline):
        return True

    last_seen = status.was_online if isinstance(status, t.UserStatusOffline) else None

    if last_seen:
        now = datetime.datetime.now(tz=datetime.timezone.utc)
        diff = now - last_seen
        return diff <= datetime.timedelta(days=days)

    if isinstance(status, t.UserStatusRecently) and days >= 1 \
            or isinstance(status, t.UserStatusLastWeek) and days >= 7 \
            or isinstance(status, t.UserStatusLastMonth) and days >= 30:
        return True

    return False

#filter #status #user

Example on how to send a file multiple times with only one upload:

file = client.upload_file(path_to_photo)
#send as photo
client.send_file(chat, file)
#send as doc
client.send_file(chat, file, force_document=True)

#file #upload #cache
Note that this only works in master branch at time of writing. Expect implementation in v1.6

Count amount of stickers installed and print some stats

sets = client(functions.messages.GetAllStickersRequest(0)).sets
scnt = sum(x.count for x in sets)
print(f'{scnt} stickers across {len(sets)} sets (average of {scnt / len(sets):.2f} stickers per pack)')

#stickers #stats