Function explain_dataflow 

pub(crate) fn explain_dataflow<T, O>(
    plan: DataflowDescription<T, (), O>,
    format: ExplainFormat,
    config: &ExplainConfig,
    features: &OptimizerFeatures,
    humanizer: &dyn ExprHumanizer,
    cardinality_stats: BTreeMap<GlobalId, usize>,
    target_cluster: Option<&str>,
    dataflow_metainfo: &DataflowMetainfo<Arc<OptimizerNotice>>,
) -> Result<String, AdapterError>
where
    for<'a> Explainable<'a, DataflowDescription<T, (), O>>: Explain<'a, Context = ExplainContext<'a>>,

Convenience method to derive an ExplainContext from the index_imports in the given plan and all other input parameters, wrap the plan in an Explainable, and finally compute and return the explain(...) result.