add_parameter.py

# When you want to add a new parameter, you only need to add in 2 places:

# In params.py:
class Params:
    ...
    my_new_param: float = 42
        

# At the "end-point" where this parameter is used:
class VeryDeepModule:
    ...
    def very_deep_method(self):
        do_something(self.params.my_new_param)