Default Value decorator.This allows you to optionally pass a "default" value into your function and have it returned in the case of a falsey value returned.

Default_Value_Decorator.py

def keep_signature(input_function):
    def to(function):
        f_name = input_function.func_code.co_name
        args = input_function.func_code.co_varnames[:input_function.func_code.co_argcount]
        kw_list = input_function.func_defaults or []
        kwargs = args[-len(kw_list):] if len(kw_list) else [] # because kwargs are last
        args = args[:len(kw_list)] if len(kw_list) else args
        d_kwargs = {}
        for k, v in zip(kwargs, kw_list):
            d_kwargs[k] = v

        kw_str = ", ".join(["%s=%s" % (x, d_kwargs[x]) for x in d_kwargs])
        doc_str = "This is a wrapper for the following method:\n\n{name}({args}{kwargs}){doc}".format(
            name=f_name, 
            args=", ".join(args), 
            kwargs=", " + kw_str if kw_str else "",
            doc=input_function.__doc__ or "")
        function.__doc__ = doc_str
        return function
    return to


def default_value(inFunction):

    @keep_signature(inFunction)
    def inner(*args, **kwargs):
        _all_names = inFunction.func_code.co_varnames[0:inFunction.func_code.co_argcount]
        args = list(args)
        new_kwargs = {}

        for name in _all_names:
            if args:
                new_kwargs[name] = args.pop()
            else:
                break
        for kwarg in kwargs:
            new_kwargs[kwarg] = kwargs[kwarg]
        
        default = None
        if "default" in new_kwargs:
            default = new_kwargs.pop("default")
            
        r = inFunction(**new_kwargs)
        return r or default
    
    return inner




@default_value
def my_func(int_value):
    """
    feeep test docstring copying. test test
    """
    if int_value % 3:
        return None
    if int_value *2 > 33:
        return None
    return int_value * 5


help(my_func)

print(
    my_func(4, default=42)
)

print(
    my_func(4)
)

Results from executing

Help on function inner in module __main__:

inner(*args, **kwargs)
    This is a wrapper for the following method:
    
    my_func(int_value)
        feeep test docstring copying. test test

42
None