So I went through and fixed up a few things, namely got rid of some redundancies and whatnot.

Changed:

• Removed magic contract values, replacing them with definitions at the top for QUIPU_KUSD, PLENTY_KUSD, and PLENTY_USDTZ_KUSD (makes upgrades and reasoning about the code easier)
• If you want to default an envar it's easier to just do os.environ.get('SOME_VAR', None) - the second parameter is the default value if the given key isn't found/doesn't have a value.
• Merged the fetch_usdtz_plenty_activity/fetch_plenty_activity/fetch_quipuswap_activity into one fetch_contract_transfers function - the only difference between these functions was the contract that was being requested from BCD, so this just passes it in
• Gets rid of fetch_all_new_transfers since it was mostly doing work to update the latest hashes, and moved that into the main watch_for_changes function, which also let's us get rid of the global ophash tracking stuff
• Returns both the transfers and the latest ophash from fetch_contract_transfers, which is used to update the different latest_*_ophash stuff
• Merges the 3 iteration loops over transfers into one guarded by contract checks

Minor Things:

• Fixed comment formatting, they should always have a space after # (so # This is a comment, not #This is a comment)
• Numbers can be written with _ that'll get stripped out at runtime (so you can write 1M as 1_000_000 which is easier to read than 1000000)
• Fixed some spacing things
• Moves fetch_whales() into the init at the bottom (separating out concerns a bit better)