Add spec to confirm integration with dry-monads Do notation
user
```ruby
require "dry/monads/result"
require "dry/monads/do"
require "dry/matcher/result_matcher"

RSpec.describe "Integration with dry-monads Do notation" do
  let(:operation) {
    Class.new do
      include Dry::Monads::Result::Mixin
      include Dry::Monads::Do
      include Dry::Matcher.for(:call, with: Dry::Matcher::ResultMatcher)

      def call(user)
        user = yield validate(user)
        greeting = yield greet(user)

        Success(greeting)
      end

      private

      def validate(user)
        user[:email] ? Success(user) : Failure(:no_email)
      end

      def greet(user)
        Success("Hello, #{user[:name]}")
      end
    end.new
  }

  it "supports yielding via Do notation as well as final result matching block" do
    matched_success = nil
    matched_failure = nil

    operation.(name: "Jane", email: "jane@example.com") do |m|
      m.success { |v| matched_success = v }
      m.failure { }
    end

    operation.(name: "Jo") do |m|
      m.success { }
      m.failure { |v| matched_failure = v }
    end

    expect(matched_success).to eq "Hello, Jane"
    expect(matched_failure).to eq :no_email
  end
end

```
assistant