Hi, my class group and I want to work in this Issue.

Group:
@Jeam-zx
@Migueldsc12
@AnyaMarcanito
@henryg311
@cuevasrja

@cuevasrja & friends if you're still interested, would you like to get started on this? I think it would be good to split this into two PRs, one for the Bot method arguments and one for the classes. Some additional pointers on both:

• for the arguments of Bot methods, converting timedelta to int should happen at
  

  python-telegram-bot/telegram/request/_requestparameter.py

  Lines 116 to 117 in 2ac5201

  	if isinstance(value, datetime):
  	return to_timestamp(value), []

  
  and corresponding new parametrizations need to be added to
  

  python-telegram-bot/tests/request/test_requestparameter.py

  Lines 98 to 101 in 2ac5201

  	def test_from_input_no_media(self, value, expected_value):
  	request_parameter = RequestParameter.from_input("key", value)
  	assert request_parameter.value == expected_value
  	assert request_parameter.input_files is None

  
  Moreover, it would be good to explicitly tests timedelta inputs for the arguments known so far. I expect that the corresponding test functions can be decorated with something like @pytest.mark.parametrize("foo_period", [42, dtm.timedelta(seconds=42)]) so that no additional test functions are needed.
• for converting arguments of classes to timedelta, please add a new helper function to
  

  python-telegram-bot/telegram/_utils/argumentparsing.py

  Line 19 in 2ac5201

  """This module contains helper functions related to parsing arguments for classes and methods.

  
  It should directly issue deprecation warnings if the input is an integer. Search for PTBDeprecationWarning in the code base to see some example on how we do that. We'll also want unit tests that ensure that the warning is issued correctly for all casses that use the conversion
• converting the int value received from telegram to timedelta should happen in the de_json method of the respective class. If the class doesn't override TelegramObject.de_json yet, add that. The test_de_json unit tests for the respective classes will have to be updated
• for the attributes of classes: Let's say we consider subscription_period. Change self.subscription_period = … to self._subscription_period = … and add a property subscription_period. Add a new helper function to
  

  python-telegram-bot/telegram/_utils/datetime.py

  Line 19 in 2ac5201

  """This module contains helper functions related to datetime and timestamp conversations.

  
  along the lines

  def get_timedelta_value(value: dtm.timedelta) -> Union[int, dtm.timedelta]:
      if os.get_env("PTB_TIMEDELTA"):
          return value
      # issue PTBDeprecationWarning explaining that in the future dtm.timedelta will be returned and encouraging users to set the env var
      return value.totalseconds()

  Here as well, we'll need unit tests that ensure that the properties return the expected value with/without the env var and issue the warning correctly

Hi @Bibo-Joshi , Sorry, we are coming back from vacation and now I am reading your message.

Yes, not all of us will be able to participate but we are still interested in contributing to the project if possible even if it is not for an academic reason.

No worries :) glad to hear that you'd like to contribute. In the meantime I've already created #4651 for the bot method part, but the class parameter/attribute part is still open. You're welcome to open a PR for that. Let me know if you have any questions.

@cuevasrja how is it looking for your? Ideally, I'd still like to get this into a 21.x release, such that we can remove any deprecation shims in 23.0