`functools.lru_cache` has a maxsize=128 default for all functions.

If a function has no arguments then this maxsize default is redundant and should be set to `maxsize=None`:

```
@functools.lru_cache()
def function_with_no_args():
    pass
```

Currently you need to add `maxsize=None` manually, and ensure that it is also updated if you alter the function to add arguments.

Hi Tom Forbes, I don't think there is a way to be sure that's the function does not take any argument. Are you worried about the lost memory when maxsize is not set?

The number of arguments is determined when the function is called (and it may be different for every call). maxsize is specified when the function is created.

In 3.9, the @cache() alias is provided as a cleaner way to create an unbounded cache.¹  There is no need to special case a zero-arity function.  Besides as Rémi and Serhiy have pointed out, we can't know the arity in advance.

¹ https://docs.python.org/3.9/library/functools.html#functools.cache