The telethon.tl.custom package contains custom classes that the library uses in order to make working with Telegram easier. Only those that you are supposed to use will be documented here. You can use undocumented ones at your own risk.
More often than not, you don't need to import these (unless you want type hinting), nor do you need to manually create instances of these classes. They are returned by client methods.
telethon.tl.custom
telethon.tl.custom.adminlogevent
telethon.tl.custom.button
telethon.tl.custom.chatgetter
telethon.tl.custom.conversation
telethon.tl.custom.dialog
telethon.tl.custom.draft
telethon.tl.custom.file
telethon.tl.custom.forward
telethon.tl.custom.inlinebuilder
telethon.tl.custom.inlineresult
telethon.tl.custom.inlineresults
telethon.tl.custom.message
telethon.tl.custom.messagebutton
telethon.tl.custom.participantpermissions
telethon.tl.custom.qrlogin
telethon.tl.custom.sendergetter