Passing config object itself to registered functions

Configuration entries marked with a `@` are treated as calls to function registries and the other entries within that dictionary are treated as function arguments. Is there a way to pass the configuration file itself as a function parameter? For example, let's say I have a registered function defined as:

```
@registry.visualizer("v1")
def my_visualizer_v1(a, b):
# do stuff
```

And a configuration file:

```
[Global]
var1 = 123
var2 = "foo"
[Visualizer]
@visualizer = "v1"
a = ${Global:var1}
b = ${Global:var2}
```

Is there a way to pass the configuration object itself to `my_visualizer_v1` and let it retrieve the values it needs, e.g.

```
@registry.visualizer("v1")
def my_visualizer_v1(cfg):
a = cfg.Global.var1
b = cfg.Global.var2
# do stuff
```

My use case is that the parameters defined in the config file are used throughout the library; only a few of them are actually unique to the visualizer function(s). I don't want users to have to remember which of the parameters a certain version of a function needs (for example, another version of the function may require additional or fewer parameters than `v1` does) and would rather have the functions themselves extract what they need from the config file.