How to pass a kwarg named ref to a Python function

[rectalogic]

librosa has an API librosa.power_to_db() that requires a kwarg named ref. How do I pass that from mojo, it seems to interpret ref as the reference keyword or something.

from python import Python

fn main() raises:
    var librosa = Python.import_module("librosa")
    var np = Python.import_module("numpy")
    var y = librosa.load(librosa.ex('trumpet'))[0]

    librosa.power_to_db(y, ref=np.max)

> mojo run p.mojo
/Users/aw/Projects/rectalogic/experiments/mojo/p.mojo:8:28: error: unexpected token in expression
    librosa.power_to_db(y, ref=np.max)
                           ^
mojo: error: failed to parse the provided Mojo source module

In Python I would pass a dict literal like librosa.power_to_db(y, **{"ref": np.max}) but dict literals are not supported in mojo.

Constructing a dict and unpacking is also not supported:

    var kwargs = Python.dict()
    kwargs["ref"] = np.max
    librosa.power_to_db(y, **kwargs)

/Users/aw/Projects/rectalogic/experiments/mojo/p2.mojo:10:28: error: keyword unpacking not supported yet
    librosa.power_to_db(y, **kwargs)
                           ^
mojo: error: failed to parse the provided Mojo source module

[soraros]

You can write

librosa.power_to_db(y, `ref`=np.max)

[rectalogic]

Thanks, that works. I found documentation describing that:

to avoid migration errors with Python code that uses identifier names that match Mojo keywords, Mojo provides a backtick feature that allows any keyword to behave as an identifier.

https://docs.modular.com/mojo/why-mojo#intentional-differences-from-python