module
   Ast::TokenHolder
 
  Direct including types
- Ast::ArrayLiteral
 - Ast::BlockStatement
 - Ast::BooleanLiteral
 - Ast::CallExpression
 - Ast::ExpressionStatement
 - Ast::FunctionLiteral
 - Ast::HashLiteral
 - Ast::Identifier
 - Ast::IfExpression
 - Ast::IndexExpression
 - Ast::InfixExpression
 - Ast::IntegerLiteral
 - Ast::LetStatement
 - Ast::PrefixExpression
 - Ast::ReturnStatement
 - Ast::StringLiteral