pub fn is_cyclic<'a>(
        &self,
        a: impl Into<FeatureId<'a>>,
        b: impl Into<FeatureId<'a>>,
    ) -> Result<bool, Error> {
        let a = a.into();
        let b = b.into();
        let a_ix = self.feature_graph.feature_ix(a)?;
        let b_ix = self.feature_graph.feature_ix(b)?;
        Ok(self.sccs.is_same_scc(a_ix, b_ix))
    }
Returns true if these two IDs are in the same cycle.
guppy/src/graph/feature/cycles.rs