For this case where the parameter(s) is required/compulsory, I'm wondering if we can move towards having the error being thrown natively by Python, instead of writing code like:

if kwargs.get("F") is None:
    raise GMTParameterError(required={"filter_type"})

Should we revisit #2896 which mentions PEP692, and also think about using PEP655's typing.Required qualifier (https://typing.python.org/en/latest/spec/callables.html#required-and-non-required-keys)? Maybe a step towards #262 is to disallow single character arguments for required parameters, so that we can have native Python errors?

The main issue is that, with the new alias system #4000 implemented, **kwargs will no longer be needed. We will still keep **kwargs to support single-letter option flags, but other parameters won't be passed via kwargs anymore.