This section provides an extended introduction to syntax/parse as a series of worked examples.
8.2.1 Modules and reusable syntax classes
8.2.2 Optional keyword arguments
8.2.3 Variants with uniform meanings
8.2.4 Variants with varied meanings
8.2.4.1 Syntactic normalization
8.2.4.2 Non-syntax-valued attributes
8.2.5 More keyword arguments
8.2.6 Contracts on macro sub-expressions