You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: decorator.rb
    path of file: ./repos/sorbet/gems/sorbet-runtime/lib/types/props
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
# typed: strict

# NB: This is not actually a decorator. It's just named that way for consistency
# with DocumentDecorator and ModelDecorator (which both seem to have
    
  def prop_get(instance, prop, rules=prop_rules(prop))
    val = instance.instance_variable_get(rules[:accessor_key]) if instance.instance_variable_defined?(rules[:accessor_key])
    if !val.nil?
      val
    elsif (d = rules[:ifunset])
      T::Props::Utils.deep_clone_object(d)
    else
      nil
    end