class Visitor < Crystal::Visitor
  def visit(node : Crystal::ASTNode)
    puts node.class
    true
  end
end

parser = Crystal::Parser.new %(
  case (a == 2 && b == 3) # cond expression is not expanded/visited
  when true then nil
  end
)

Visitor.new.accept parser.parse # Crystal::Case
                                # Crystal::When
                                # Crystal::BoolLiteral
                                # Crystal::NilLiteral