<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def default_values_of(func):
 """Return the defaults of the function `func`."""


    signature = inspect.signature(func)
    return [k
            for k, v in signature.parameters.items()
            if v.default is not inspect.Parameter.empty or
            v.kind != inspect.Parameter.POSITIONAL_OR_KEYWORD]