class T::Private::Methods::DeclBuilder

def finalize!
  check_live!
  if decl.returns.equal?(ARG_NOT_PROVIDED)
    raise BuilderError.new("You must provide a return type; use the `.returns` or `.void` builder methods.")
  end
  if decl.bind.equal?(ARG_NOT_PROVIDED)
    decl.bind = nil
  end
  if decl.checked.equal?(ARG_NOT_PROVIDED)
    default_checked_level = T::Private::RuntimeLevels.default_checked_level
    if default_checked_level == :never && !decl.on_failure.equal?(ARG_NOT_PROVIDED)
      raise BuilderError.new("To use .on_failure you must additionally call .checked(:tests) or .checked(:always), otherwise, the .on_failure has no effect.")
    end
    decl.checked = default_checked_level
  end
  if decl.on_failure.equal?(ARG_NOT_PROVIDED)
    decl.on_failure = nil
  end
  if decl.params.equal?(ARG_NOT_PROVIDED)
    decl.params = FROZEN_HASH
  end
  if decl.type_parameters.equal?(ARG_NOT_PROVIDED)
    decl.type_parameters = FROZEN_HASH
  end
  decl.finalized = true
  self
end