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: kms.rb
    path of file: ./repos/mongo-ruby-driver/lib/mongo/crypt
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
# rubocop:todo all

# Copyright (C) 2019-2021 MongoDB Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with
    
        def validate_param(key, opts, format_hint, required: true)
          value = opts.fetch(key)
          return nil if value.nil? && !required
          if value.nil?
            raise ArgumentError.new(
              "The #{key} option must be a String with at least one character; " \
              "currently have nil"
            )
          end