//! This module implements *Cluster graphs*. This is a representation of DOT graphs that preserves
//! subgraphs (such as [`crate::ast::Graph`])s, while simplifying the internal representation (e.g.
//! edges are not chained, node, edge and subgraph statements are separated, etc).
//!
//! The main structure of this module is [`Graph`].
use crateGraph;
use crateAList;
use crateNodeSet