Access default value in the type AST

Hello!
I wonder if there’s a way to access the default value of a type while parsing the AST.
I’m building a gem to translate types into other structures and having the default value would help.

Types::String.default("test".freeze).to_ast
# => [:constrained, [[:nominal, [String, {}]], [:predicate, [:type?, [[:type, String], [:input, Undefined]]]]]]