why not doing:
```
parameters = {
   'value_label': '# checks in a non-OK state',
   'message': '%d checks is/are in a non-OK state',
}
parameters.update(params)
```
and use `parameters`

instead of
```
overridable_params = {
    'value_label': '# checks in a non-OK state',
    'message': '%d checks is/are in a non-OK state',
}
params.update({k: v for k, v in overridable_params.items() if k not in params})
```