pub fn metadata(
        &self,
        feature_id: impl Into<FeatureId<'g>>,
    ) -> Result<FeatureMetadata<'g>, Error> {
        let feature_id = feature_id.into();
        let feature_node = FeatureNode::from_id(self, feature_id)
            .ok_or_else(|| Error::unknown_feature_id(feature_id))?;
        self.metadata_for_node(feature_node)
            .ok_or_else(|| Error::unknown_feature_id(feature_id))
    }
Returns metadata for the given feature ID, or `None` if the feature wasn't found.
guppy/src/graph/feature/graph_impl.rs