human
Here's a good function header given the following:
I wrote the below code

    if (not get_function_code(func).co_argcount):
        raise LookupError('func    not    found')
    assert (get_function_code(func).co_varnames[1] == arg)
    if (retval is None):
        @wraps(func)
        def __sympifyit_wrapper(a, b):
            return func(a, sympify(b, strict=True))
    else:
        @wraps(func)
        def __sympifyit_wrapper(a, b):
            try:
                if (not hasattr(b, '_op_priority')):
                    b = sympify(b, strict=True)
                return func(a, b)
            except SympifyError:
                return retval
    return __sympifyit_wrapper

What's a good function header?
assistant
#Here's a good function header.

def __sympifyit(func, arg, retval=None):