/// ZPL abstract syntax tree types.
/// Re-exports from the diagnostics crate.
/// JSON serialization helpers for the AST.
/// ZPL emitter — converts an AST back to formatted ZPL text.
/// ZPL lexer — tokenizes raw input into a stream of borrowed tokens.
/// ZPL parser — converts tokens into an AST.
/// Re-exports of spec tables types used by the parser and validator.